Final Fantasy series of games, and sci-fi/fantasy fans also love his illustrations in Vampire Hunter D. More casual anime fans may have seen his work in Neil Gaiman's Sandman: Dream Hunters.
If you'd like a sneak peek at the exhibit, I've got some video footage from the New People Center opening day that includes it (the exhibit starts about 20 seconds in). There are some gorgeous pieces in there, highly stylized, and fans of older-school anime will particularly appreciate some of it, I think. (Note: it was shot on the handcam sans tripod, and it's sped up, so sorry about the jitters! I swear I wasn't tweaking.)
What do you think? I bet this style of Amano isn't what everyone wants to hang on the walls, but man, there were a couple of pieces in there I'd LOVE to have.