I didn't make all that much Psychonauts art (save for concept sketches of my own character), but I do have some relevant Loboto art that I'm sure many have seen, but perhaps some have not.
Postasylum is probably the best pic I ever did, and I've never done anything close to this good since. ;_; I dunno, maybe one day I'll be all motivated again.
Cinder is another Loboto-based art... I'm actually making these more serious than silly.
Quick sketch of Loboto. Somehow, I got the style almost right.
Becky and Jasper trade that I did. Oh, look, it's actually not Loboto art, but whatever.
So there you have it. I haven't really done anything since.