VGChartz was helpful with recommending me games awhile back. I ended up hauling quite a bit.
Castlevania: The Dracula X Chronicles (A must have if you enjoy Castlevania. One of the best games on the system.) It's currently at Gamestop Gameday sales for $10 and will be $8 in two days once they do the "final clearance".
Daxter: It's real good and damn cheap. You can get it used at GS for $5 or a complete copy on fleabay for $7 or less.
Disgaea 1: I chose this over Jeanne D'Arc as my SRPG of choice. I already beat FFTactics a ton on the PS1 and this will most likely eat up the most of my time. Since I have little time for RPGs compared to before I only chose to get one SPRG. Keep in mind this will probably be the most expensive game you will buy on the PSP, at least it was for me.
FF1 Anniversary: ... yet at the same time I bought FF1 because I still believe FF1 is the seconnd/third best FF made, and this is the "ultimate" version so to speak.
Gitaroo Man Lives: If your into Rhythm games this is pretty damn good although quite short. I scored a sealed copy for $9 shipped. It's a shame Rock Band/Guitar Hero will probably kill off the genre when it comes to "unique" rhythm games. Just look at the sales. Highly recommended.
Mega Man Powered Up: How this has low scores is beyond me. This is basically a remastered version of Megaman 1 with so much replayability It's not even funny. Pick this up. NOW
MGS:PO: Metal Gear exclusive to the PSP with awesome Single Player campaign and some online thrown in. Need I say more? PSP GET!
Phantasy Star Portable: Hack and slash heaven. A must have if your into any of that stuff. Oh, and It's already cheap to.
Prinny: The other "expensive" game. Another must have though.
Ratchet and Clank: Size Matters: If for some reason you don't own a PS2 or want a great portable pocket adventure then this will fit the bill. At most Targets for $10 or less right now, and pretty cheap everywhere else.
Silent Hill Origins: Again, if you don't own a PS2 and want awesome portable experience then you must get this. It's also $10 or less at many places, as part of the Gameday sales at Gamestop (and being clearanced in a few days to $8).
Untold Legends: Warriors Code: A forgetten great hack and slash that will keep you busy for hours. Unsure if online is up at the moment however.
Brave Story: Probably the only "unique" non-SRPG I would highly recommend at the moment, though there are a lot more out there this seems to be the "best".
Honorable mentions: SNK Classics Vol 1 and Sega Genesis Collection. Metal Slug Collection, Star Ocean 1+2, Burnout Legends, Hammerin' Hero, Jeanne D'Arc and of course Patapon.
I couldn't get into Resistance yet but I'll give it another go (need second analog plz?) and didn't mention Tekken DR cause I am waiting for the Tekken 6 "port".
It's just that simple.
