I'd worry more about casing in that window and door with wood trim, replacing the carpet, sofa and even organizing the shelves themselves. How about some rot of bin or storage for the household products on display? Looks like you have a decent save with lots of potential.

I was going to write some ideas about garlands and fairy lights, but then I found this post which includes some nice (and some not so nice) ideas:

http://www.ehow.com/how_8760728_decorate-bookcase-christmas.html

To me, anything that not only looks but smells like christmas too is a bonus, so I would definitely make a simple garland using fresh foliage. You could also put it over your window. Or make or buy a wreath and put it on your door.

I don't think having an unfinished house has to influence the way you decorate. In a way it's even easier: you can cover anything you don't want to be seen with christmas decorations :)

I hope you enjoy your first real christmas in your house!

You have a lot of black and grey in that room and limited light. It looks very dark. Is this the look you're going for?
I can see that the room is still unfinished and if it's not going to be done by Christmas, you can either cover it up or work with it. If you're going to cover it up, why not wrap the windows and doors like Christmas presents with wrapping paper and bows? If you don't want to cover it up, go with industrial chic with traditional christmas themes in metal and wire. But whatever you do, please get some light into the place. If you're not going to paint those light sucking black bookcases, drape them in lots of twinkly lights. And put some color on the sofa. Instead of red and green pillows, why not coral and lime? Or white and raspberry?
Here are the HGTV holiday house videos. Some of these ideas might work:
http://www.hgtv.com/search/results.do?hgSearchString=britany+simon+holiday+house

You just need unity is all, and a change of pallet. Target has star-shaped white lights that would be fun. Add some garland and some winter-themed decorations to the shelves (like santas, snow globes, and so on and so forth) in front of your stuff :) The other option would be to use furniture tacks to create curtains the length of the shelves, and tie them back with some decorative cords and tassels. Then you could add matching curtains, a throw, and decorative pillows to your furniture. Maybe even a cheap rug (which you can often get in places like Walmart *shudder*). When it's not Christmas though, consider changing your color pallet to something lighter. You don't have enough light in this room for such dark furniture. You can paint your shelves and add either furniture covers or large throws and pillows to your couch.

You just need unity is all, and a change of pallet. Target has star-shaped white lights that would be fun. Add some garland and some winter-themed decorations to the shelves (like santas, snow globes, and so on and so forth) in front of your stuff :) The other option would be to use furniture tacks to create curtains the length of the shelves, and tie them back with some decorative cords and tassels. Then you could add matching curtains, a throw, and decorative pillows to your furniture. Maybe even a cheap rug (which you can often get in places like Walmart *shudder*). When it's not Christmas though, consider changing your color pallet to something lighter. You don't have enough light in this room for such dark furniture. You can paint your shelves and add either furniture covers or large throws and pillows to your couch.

LED battery-operated tea lights with some pine or holly boughs in the open areas of the bookcase ought to do the trick. Thre are also lots of christmas tree alternative ideas for small spaces here:

http://www.houzz.com/ideabooks/966872/list/30-Beautifully-Inventive-DIY-Christmas-Decorations

The branches instead of a tree would work well right where your standing fan is.

I have a long string of fairy lights that I tape along a book shelf as a narrow triangle. Then I put baubles and anything else I have that could hang on a christmas tree along the boards (I use tape but little hooks might work). It looks better than it sounds and is my version of a space-saving christmas tree (but I celebrate with my parents who have a real tree).

The size of the furniture in this space really bothers me. Can you replace these bookcases with floating shelves and a smaller scale TV bench? Considering the height of the ceiling, maybe you can make a variation of Machandel's suggestion and hang several strands of lights from the top of the ceiling on the TV wall all the way to the floor in a triangle shape. It could look like a Nutcracker tree in scale. Also, did you know you can run a fireplace app or youtube video on your TV? So, even if you don't have a fireplace, it will look as warm and cozy as if you do. Hang some stockings from a floating shelf over the TV and make it look like a mantle. Voile! Instant warmth.

Kudos to you for deciding to get festive in spite of the work in progress! I'm going to assume that you don't want advice on huge projects, since you are in the middle of huge projects, and fitting in others would only set you back! I'll try to keep it cheap, too.

So, since you need to work with what you have, I would suggest starting there: with what you have. Take a look through your house and whatever you have stored away. Note anything that would work. Since you're trying to draw attention to your decorations and not your work-in-progress, go for cohesion. Do you have a theme, like stars or snowmen? Or a strong color scheme? For example, I round up all my red and gold stuff and group it together for Christmas. (Traditional, I know, but I adore red! Blue and silver, a frosty green, or silver and white would also work.) If you have a favorite collection, that might be a good starting point.

Pack away whatever excess you can from your bookshelves, then incorporate the rest of it. For impact, group sets together. Tuck in bits of greenery or florals (real or fake) throughout, again to draw it together. And since your space is a bit dark, bring in some lights. Rope lights, LED candles, string lights, lanterns, whatever.

Then add touches throughout the rest of the room to bring it all together. If you want to conceal the gaps around your door and windows, garland may be your best friend! Or use 6" tulle, like you buy on a roll. It's available in tons of colors and is fairly affordable.

Another idea I almost forgot . . . you can add color or texture to the back of the shelves, too! Cut thin poster board or cardboard to fit the space (make it a snug fit) and then cover it with fabric, gift wrap, wallpaper, or printed tissue paper. Push it into place, and it should stay on its own, but a little sturdy pull tab (like ribbon) on one edge will make it easier to remove. Instant drama!

Good luck!

Looks my livingroom. Espresso coloured bookcases (that don't hold books), dark TV stand in between and dark coloured furniture. My space has white walls and a lot of natural light, so the dark furniture offsets itself. I'd say, throw on a white or red throw on the couch (if you don't want to waste money, opt for the white). Hang a wreath behind the couch on the wall. Certainly a Christmas tree belongs in this, instant colour, instant light and a focal point. Probably best place is to put it by the window, it will hide the missing window framing. It already looks like the TV isn't centered, so shimmy down the couch/chaise and store the brown wooden chair (?) for the holidays. Buy Christmas decor that works with your colour palate already so there is no colour clashing. It also avoids having to put items away during the holidays. Less is always more. Since I like things to match, pick items that match your Christmas ornaments and lights. Nothing is more painful than veiwing an incoherent room.