A mirror.

I'm not seeing the problem - What you have is fine.

Sorry but it is about Small Cool 2011: I forgot to post a photo to my bedroom for the contest. Anybody knows how do I post now?

I would remove the shelf and have a very large piece of art, something really colourful and modern, leaning in that space.

I think that because you have so many smaller things on display, a large and colourful piece of art would really make that space pop (in a good way).

I don't know about what else you could put on the shelves, but for the back of it, you could put some wallpaper in temporarily.

Anything but a TV.

Get an interesting found object or art piece, à la Obsolete, and then switch the shelf and background color to match it. With luck, you won't have to.

If the shelf is removeable, you could hang a painting or large photo in there...

Or how about books?

What you already have is fine, too.

(Also, I would remove the clutter from the shelves to the right of the fireplace and put some bigger beautiful pieces there. I am sure what you're displaying is precious, but it's too small for those shelves and reads as clutter.)

A mirror in the back? Use double stick tape and add some cool wrapping or wall paper!

I agree with Caralyn and if you can figure out a way to light it I think that would help. I've seen some pretty low profile battery operated tap type lights. You could just stick them to the top of the built in.

@Sussu - if you look on the left side, there's already a TV there.

I agree with everyone else. Mirror or art.

I agree that it looks fine as is. But if you want something different, I'd take out the shelf and get a round, framed mirror. You have a lot of rectangular pieces, so a round piece would be a nice contrast. However high you hang the mirror, leave some space to keep a plant or flowers on the mantle to add another organic shape.

you can cut a piece of cardboard the same size as the space and cover it with a patterned fabric and then tape it in the space so that it looks like it has a wallpaper background. Then, put the shelf back and dress it like a library, ie, some books, some knick knacks etc... go to Nate Berkus' show website to see an example

Currently in the "designers' community" there are two things being touted and suggested that I think are simply hideous: the first is a real or imitation animal rug (ugh!) and the second is a television above a fireplace (I agree with Sussu about this.) If this were my room I would raise the shelf up a bit, and have about three plants requiring low lighting (philedendron, pothos etc.) on this shelf. I would house the plants in a planter from a garden centre the same size as the shelf...perhaps painting it black.

I would say that the problem is that there's no white trim anywhere else in the room. It feels disconnected. Ideally, it would be nice if you could paint the wooden cabinets to the right white- that way it looks like a uniform built-in bookshelf. (Maybe ask your landlord?) And then I would replace the glass shelves to the right with painted white ones. Then just display pretty things- making sure the two bookshelves are connected with their contents and aesthetic.

I have a different but also challenging mantel. We put a folk art piece that consists of a regtangular wooden box with a tin star on top -it's cool and it makes a visual triangle out of what used to be a bulky square - maybe look at Day of the Dead stuff? Closest quick thing I can find is something like this link:
http://www.tumbleweedgifts.com.au/shop/inde
x.php?act=viewProd&productId=27

If the shelve is removable, take it out and put in a colorful modern art. Then, layer it with two white vases for contrast (one tall, one short) with two vases side by side. (left or right side of mantle) Add three small tea lights in the center and voila, now you have a beautiful focal point!

You've gotten a lot of great input, especially ideas about bringing in a little more color there. I noticed oyu have a very bright rug. Maybe you could bring that color up some, or a variation of that hue.

I agree that the nook looks out of place largely because it's bright white and the only other white elements are the door & your photo matte above the tv. I thought that reframing the artwork above your sofa in bright white frames (IKEA) possibly even with white mattes to bring that white over to the other side of the room. I think the white frames coupled with some of the ideas posted about your nook dilemma would make the room look much more balanced.

Hope it helps!

~Jacci

use it as a little bar area

i think that what makes that wall unsettling is that all of the strong lines are vertical. i would carefully wrap and put away those glass shelves and get one or two white painted wood shelves to put in that space instead. i would try to find larger and more bold items to put in this alcove, some of them black. if you wanted to go with a different background (fabric, wallpaper,
mirror), i would put it in this alcove and not the one above the fireplace.
you should try to have anything you put in the fireplace alcove emphasize the horizontal. in face, the black candle holder is fine. on the shelf above it perhaps a spreading or draping plant. it would be especially effective if part of the plant cut across one of the sides of the fireplace structure. perhaps also put a standing sculpture on the hearth--again breaking the upright lines of the fireplace alcove.

Cool spot! I agree with the commenter that suggested talking to your landlord about painting the built-ins next to the fireplace. It does look odd that they are wood-tone while the rest of the trim in the room is white.

Failing that, remove the shelf and find a large mirror to fit the space that has a wooden frame that closely matches the color of the cabinet doors nearby. Maybe then pop a plant in front of it - just one, in a brightly glazed pot. Keep it simple.

Further, I'd replace the stuff on the glass shelving unit next to the fireplace with larger, simple white pottery peices (inexpensive and easy to find) that will tie in the trim color and pop against the darker background, and also a couple of brighter pieces to bring the color up from your rug. What you have now is doesn't do anything for the space and looks a bit cluttery - is it barware? If so, stash as much of it in the cabinets as possible and maybe include a just a few pieces on the countertop below for easy access.

Have fun and stay flexible - you're likely to change it several times before you find out what works!

I was immediately thinking either a mirror in an ornate frame that would fit the opening (with the shelf removed), or a big bold piece of art (which can be a DIY thing).

I also agree with tmoore's suggestion of talking to the landlord and painting the builtins next to the fireplace (and putting bigger items in there, too).
Also, I would put something horizontal above the door which would visually elevate the height to that of the built-in on the other side of the fireplace.

Take out the shelf and find a piece of art that fits the space.

I agree with the art recommendations, but I think it would be really interesting to find or make a piece of artwork (ideally on a stretched canvas) that fits that space perfectly.

My sister had a doorway to nowhere in her former living room. Her solution was to commission a work of art from a friend that fit the space. The doorway made an excellent frame.

The extreme white-ness and vertical-ness of the space is currently demanding to be the focal point of the room.

The way I see it, you can either embrace the odd space, and allow it to be a focal point -
maybe take the shelf out & hang an assortment of these: http://www.westelm.com/products/hanging-glass-bubble-collection-c083/ or some other odd/striking vertical piece to your liking.
OR
you could opt to balance the overall composition by hanging some white gallery frames (or using a ledge) on the adjacent wall (above the TV).

I would also suggest painting your tv stand white.

Does anyone else think maybe those cupboard doors to the right of the fireplace could be white?

I would paint it the same color as the wall with shelves next to it..then just some nice sculptures,
art pieces, ceramics.

I agree with a lot of previous suggestions, but just for the sake of something different:

What about having a piece of plywood cut to size for the back, and staining it to match the cabinets, and securing it with double-sided tape? If you remove the shelf, you could then hang or prop a piece of art with some strong colors (the turquoise from the rug, the red from the rug, and maybe the black from the entertainment unit/fireplace). It would pull all the elements in your space into the focal point.

I would also keep the plant for an organic element.

This wasn't part of your question, but I also suggest adding some more turqoise and red elements around the room in pottery and throw pillows. It would kick the room up a few notches.

the problem, at least in the photo, is the big black media center. Lose that and you are back in the game.

If you have to have that media monolith, and it's yours, and it's paintable, then echo the browns and beiges and buffs and whites that are so nutty on the other wall and have fun with it and it won't be so, umm, alien dark star.

Leave the shelf! Put some grren short plants (grass) on the bottom, hang a circular mirror above the shelf and stack a few books on thr shelf.

I think her tv stand is fine, especially with the "white" drawers, since the fireplace is a black insert in a big white... thing. That said, I'm not sure I see the problem. On the other hand, it's right by the door (to the outside), isn't it? Put some baskets there to toss stuff in for a landing strip?

(... every time I read "landing strip" or "corral loose items" I get annoyed now. >.>)

A mirror would be pretty awesome. You can also keep the shelving and put other decorations there to give it depth - I like the flowers / plant now.

And I'd keep the candles. Those are pretty adorable.

Create a secret compartment by hanging a giant photo or poster over it. Use it to hide clutter when guests come over. Or for pirate booty if you have any ...