Wow, what an impressive restriction.  I honestly don't think you're going to find someone like that, it's like asking for someone who creates paintings for a living but doesn't show work at a gallery.  Or an accountaint who isn't willing to work for a business.  Making art for games is just how pixel artists make money.  I suppose it's possible to have someone who has found a way to make pixel art for a living without making anything for video games, but it's a niché inside a niché.  You are narrowing your chances even further by asking for this type of person at Open Game Art.

Here's my favorite pixel art article.  I also like the Retronator Magazine, which seems to be more along the lines of what you're looking for.  It should also help you find those pixel artists who focus more on non-game pieces.

Good luck on your paper!

Most pixel artists I know dont do any form of exibition unless its a hardware demo but those are usually intense collaborations. You can check out www.pixeljoint.com where there are tons of artists who make and get paid to make just pixel art without the intent of puting it in a game.