But seriously, try looking around the classified section here on gamedev.net and Prinz Eugn has some packages of stuff and knows some good places to look, so I'd ask. Or you could look on Pixel Joint or deviantart to find an artist for an indie or pro project that has some budget. For a tiny, one-man indie project with no budget, I suggest looking here. (It's a link to Gimp ) That one is serious though. It isn't that tough to do some decent pixel art with practice and going through a couple of tutorials around the web.
Ha, thanks for the shoutout, Dave. Not sure about Wolfenstien, but there are tons of free DooM (original) resources available, which doubtless will have something appropriate. Here's one with a BSD licence: http://doom.wikia.com/wiki/Freedoom If you want to sell your game, you'll probably need to read up on licenses, and I'm not even going to pretend to know the ins and outs of them.
Hmm... this might be what you're looking for, too: http://www.areyep.co...reLibrary.html. (has both tutorials and some textures posted). Couldn't find anything about licensing, looks like they are open for anything.