The last episode of Community ends with a piano piece that was maddeningly familiar to me, but I couldn’t quite place it. Apparently it was from My Dinner With Andre, but knowing that fact didn’t scratch my itch since I’ve never seen that movie at all. So then I looked for the piano music on Youtube and found the answer in the comments: Gymnopedie No. 1 is the piece used in the trailer for The Disappearance of Haruhi Suzumiya. Whew, I’m glad I found that out, not knowing the answer was really starting to bug me. And to think, I would have been simply out of luck in the days before the Internet. Thank you, Youtube! Also Internet Movie Database, that site has answered innumerable questions for me as well.