A large mirror or a bookcase would do the trick.

I was also going to say curtain, just pretend like it's a big window. You could also hang some artwork on it, like it's sort of part of the wall.

If you don't want a curtain, you could prop up a large mirror against the wall, but it will be more costly.

A folding screen?

Hanging curtains on both walls of the corner would work, but I suggest you look into a folding screen. I can see you have an interest in Southeast Asia from your decor and a screen might fit in nicely.

I'm with Comicgeek. Lean a nice large mirror against the wall, covering the door. It'll create a lot of light and cover your door perfectly. :)

You could put a large mirror there, or hang fabric over a portion of the wall, if it works for the wall. Another easy solution would be to put a folding screen in that corner, which would frame your reading nook. Putting a palm or other large plant along with your chosen solution would also help anchor that area.

Curtains.

The problem with a folding screen is that most of them aren't tall enough to completely hide the door

take the hardware off the door and hang a Hovet over it.

I like everyone's suggestions. I think a folding screen or curtains would be great!

A tall bookshelf would cover up the door. Another option that might look neater than a curtain is to get some lightweight stretcher bars from an art supply store and stretch plain canvas on them (not hard--you just need a staple gun). Get something large enough to cover the door and then some, in order to define the reading nook area. Then paint the canvas.

Paint the door the same color as the wall.

bookcase or entertainment center.

I agree with the curtain suggestion - if you can, I would hang it from a ceiling-mounted track the whole length of the wall (not just in front of the door). The lobby of my apartment building has that behind the front desk and it looks fabulous.

buy a canvas that's slightly larger and paint it or wallpaper it.

I agree with floor to ceiling curtains along the whole wall. Soft walls, I think they are called, are very dramatic and cozy at the same time.

A large bookcase might be able to cover the entire thing.

Have you thought about creating a door that's flush to the wall? you would have hidden hinges that are attached on the inside of the closet, and have a door (same color as the wall) that sits flush to the wall to make it appear as though it's just a wall.

A couple pictures of what I'm talking about - http://egtcontracting.com/yahoo_site_admin/assets/images/39_gpn_living_room_after_closet.34852801.jpg

http://www.thathomesite.com/forums/load/wood/msg010354099543.html?4

I would get rid of the knob and hang a lot of pictures all over the door in various frames. Or even without getting rid of the knob, but then I would also add some brass figures. And i would put high but thick plant in the corner.
And is this evil-looking cat on your chair?

Use wallpaper or wrapping paper and wrap the door - try removing then replacing the knob so that it doesn't look too wonky, or just remove the knob entirely. The doorframe will look like an actual frame. Then put a large plant there.

An artwork panel "curtain", such as from IKEA. They have many patterns to choose from and hang from ceiling very easily.

Another vote for floor-to-ceiling curtains across the whole wall.

i had an idea that a variation of some above. . . which is to create a canvas. however, i would create two or three and place them around your room in a way that makes it look intentional and part of your scheme. any of the ideas mentioned above 'might' appear like they are bandaids to cover a door! this might hide that fact a little better. i would go to your local art store, by the cheap wood frames in a size that will cover your door, get two more of the same thing, and go get some fabric you love (ikea as is would be cheap?) and cover those with a staple gun. you could do it all for under 100. and you can take it with you!

bookshelf. tall. filled with books. found objects and a lamp!

It's a very idiosyncratic solution, but you could use rasterbator to cover the wall with an interesting image.

Rasterbator gives you a multi-page document rasterized blow-up of whatever image you give it. The pages can be trimmed to fit exactly on/around moldings and knobs, and affixed to the wall with scotch tape, which I found easy to remove without damaging paint/finish.

My old kitchen:
http://www.jerde.net/thomas/recent_photos/image_viewer_2.html

I hadn't anticipated how much it would hide my door. It was almost problematic how invisible it became.

I have the same problem in my dining room and now have a few ideas to try - thanks!

I may combine the "use the door frame as an actual frame and wrap it" and the "stretch your own canvas" ideas and stretch some canvas and mount to the door with doorknob removed so that the door frame looks like a picture frame, and invite friends to have at it when they visit...

Take the door off the hinges and store it - you could hang a piece of fabric with a nice print on the inside of the door stretching it across. It would be cheaper than artwork. Plus the door frame will be the frame for your new "art". Or instead of the fabric place a nice tall bookcase in the area where the door used to be.

Later when you move, put the door back on.

Wow, le_sacre, that's amazing!