Nice list! This reminds me of number of good games that I didn't play (because of time) or just forgot later.
I played through Hammerin Hero multiple times just for fun. I really like the light-hearted theme of the game, which never takes itself too seriously. It's interesting that all IREM games take this approach, including SteamBot Chronicles and the Blockus board game on PSP. Also, it's fun to comeback sometimes and try to find good scoring paths through levels.
Also played Rock Band alot. It's fun and quite suited for the PSP. I would have liked to get all Golden 5, but I got burnt out. Still it was fun while I played it. Eventually there were 2 or 3 songs where I had to content myself with a 4. There are sections where there is extremely closely spaced strings of alternate notes (like in Pain Killer). I can't seem to get those correct, and I think those would have been the problem in the long run.
Also nice to see Downstream Panic so high. I tried playing Patapon but got somewhat confused by the interface.