maybe do some builtins, or if you are looking for the modern look you could paint the wall with a couple different colors, and maybe a design. Look at page six of the Benjamin Moore Atlantic Northeast Paint Brochure for an idea.

Here is a link that might be useful: brochure

First, it would be a little easier to make suggestions if we had more pictures--what's opposite the window wall, what does the couch wall look like?

What do you want to be able to do in this room? Watch TV looks like a given, but what else? Entertain friends, read, surf the net (on what, desktop, laptop, tablet?), play video games, listen to music, eat snacks, eat meals, do hobbies or crafts? Do you need a home office space? More storage? Does that wall back onto your bedroom, or the neighboring apartment?

Off the top of my head, how about a sleek Mid Century Modern credenza? Put the TV on top and then you have tons more storage inside.

Or a new, larger TV stand, flanked by bookcases. Gives you a place for all the electronics associated with the TV, plus more storage.

Or a nice, new TV stand, plus a desk, bookcase and file cabinet for a home office.

If you are really short on storage space in your apartment, I'm a big fan of the great wall o' storage. Look into bookcases that come with optional doors, and put three or four of them along that wall. The Ikea Billy system is one example. Add some doors to hide some of your stuff, so you don't have to be super neat all the time. Use bins or boxes to hold other stuff--bookcases are not just for books. The Ikea Expedit is another option--comes in a variety of sizes and shapes, so you could easily work the TV into the design, and has doors and drawers that fit into the cubbies to make them more useful.

It's going to be difficult to fill that entire wall up with art or a mural. You need a little bit of furniture on that side of the room, so that the room looks more balanced.

When it comes to artwork, I'm in the school of "live with the blank wall until you find something you love." But not everyone else is. I'd check out Apartment Therapy for some cool ideas on DIY art. I've see chalkboard walls, plywood art, all sorts of things that might spark your imagination.

I suspect storage would be welcome, so built ins would be nice, or a substantial piece of furniture that could be used for storage...maybe a large credenza or sideboard...maybe incorporating the tv as part of the total arrangement. You can buy inexpensive book cases at IKEA and then have them pulled together with crown molding at the top and a board at the bottom. You can fill them with baskets for storage items.

Otherwise a quick and inexpensive way to cover a wall is with fabric on stretcher frames...

If you have a small living room, maybe decorate it with mirrors?
Mirrors reflect lights and make the room looks bigger.

Some ideas for example: http://www.smallroomideas.com/decorating-small-rooms-with-mirrors/

You can also combine decoration with storage, if you have a small apartment. For example shelves for books and some small decorative items on that blank walls? The colors from the books might help brighten it up a bit.

Here is a link that might be useful: Combine storage and decoration for small living room

I like the wall of bookcases Annie posted; but I have to say that I find it very strange, not to say, disconcerting, to have a whole wall of bookcases with hardly any book. A flower pot or a picture frame or two pillows per shelf! And only yellow books allowed, apparently.

As others have indicated, you need to look at that wall in the context of the whole room and what you do there.

I would pull the TV away from what looks like the baseboard heater under the window.