OMG there are just so many great games on the PSP . My advice is to go on metacritics and check out the top 50 games or so ;)

There are some good games on it such as Castlevania:Dracula X Chronicles and Jeanne d'Arc.

They need to stop kidding around and port over a Bleach title for the PSP. Right now i'm playing Wild Arms for the PSP. My PSP has seen alot of miles in the past ,but TEKKEN 5and LUMINES II never grow old. Oh, and Castlevania S.O.N. is a must.

 i love that picture of Chuck getting RAMPAGED, NICE.

 The bolded games are the ones that I plan on getting. I've tried two of these games (R&C: SM, GTA LCS) and they were lots of fun. I also plan on getting Star Wars Battlefront: Renegade Squadron, which I also enjoyed. I'm gonna pick up a PSP for my birthday (which just happens to be the same day that Secret Agent Clank is released).

Do it! I wanted to purchase a PSP for the Sprg trifecta (Joan D''arc, Disagaea , FFT) and I bought one a month ago and couldn't be happier (and I HAVN"T EVEN BOUGHT ANY SRPGS YET!) I have bought Daxter and patapon so far. Patapon is porbably my 12th or so favoirte game ever. I would give it a 9/10 repetitive, but it is so unique, unlike anything I have ever played. Daxter is alright, it's like a linear crappy version of super mario sunshine with 1/3 of the creativity.

To help you with games, here is my list (/10 is how much I want the game/liked the game, not a review)
also- PSP is great for sports, shooters, and puzzles, which arn't on my list. Sports you know what you want, shooters I recommend Metal Gear Solid portable ops, syphon filter games, and medal of honor heroes. Puzzle I recommend Lumines and Crush.
list when it comes to games, DS has more, but PSP has more than enough games to satisfy my needs (and I have a DS aswell :D)
PSP GAMES
1. Final Fantasy Tactics: War of the lions (10/10)
2. Patapon (9/10)
3. Sega Genisis Collection (9/10)
4. God of War:Chains of Olympus (9/10)
5. (Hopeful) FF7 (PS1) (9/10)
6. Loco Roco (9/10)
7. Tales of Eternia (UK import $35, its worth it) (9/10)
8. Jean D'arc (9/10)
9. Disagaea: Afternoon Of Darkness (9/10)
10. harvest moon: boy and girl (8/10)
11. Kingdom Hearts: Birth by Sleep (8/10)
12. Rachet and Clank: Size Matters (8/10)
13. Daxter (8/10)
14. Riviera: the promised land (8/10)
15. Spyro the dargon (ps1 download off of playstation store) (8/10)
16. Ape Escape: on the loose (8/10)
17. Burnout: Dominator (8/10)
18. GTA: Vice City Stories (8/10)
19. Valkeryie Profile: Lenneth
20. GTA: Liberty City Stoires (8/10)
21. Final Fantasy 7: Crisis core (8/10)
22. Metal Gear Solid: Portable Ops (8/10)
23. Metal Slug Anthology
24. Castlevania: The dracula X chronicles (8/10)
25. Sonic Rivals (7/10)
26. Tales of the World: Gradient mythology (7/10)
27. Mega Man Powered UP! (7/10)
28. Sonic Rivals 2 (7/10)
29. Me and My Katamari (7/10)
30. Innocent Life: A futuristic Harvest Moon (7/10)
31. Wild Arms XF (6/10)
32. Final Fantasy Anniversary Edition (6/10)
33. Grand Turismo Portable (6/10- this will probably be great, but I personally am not that interested)

Hope that helped. PSP is definatly worth buying. You can also hack it and play SNES games of any game Sega Geninis collection doesn't cover (It think it had 40 games or so, 80% of which are good)