mmm
Megaman Powered Up - it's a remake of the original but the robot masters got new attack,it got a new shiny coat,new robot masters to bring the number to 8 and the levels are redone,it also has a level editor,the ability to play as robot masters and special challenge to see how well you fare with certain gimmicks like time man slow time ability... pretty good stuff
Jeanne d'arc - animu joanne d'arc SRPG by level 5,the game it's pretty standard SRPG stuff but the whole jeanne d'arc plot gives it a pleasant original twist... at least until the game gets hit with the stick of RPG cliche's near the end
Monster Hunter Frontier - actualy i haven't played this so why i'm putting this on the list? because i played the wii version and it's very good! basicaly a group of 4 players bands all together and then they go punching a giant monster to death,and then with the hide and fangs of that monster they make new weapons and armors,it's kinda like playing diablo if you never fought small fries... the controls are a little clunky (actualy especialy clunky on the psp since you have to move the camera with the digital buttons)
and to be fair it's not much fun to play alone (and there is no online with the psp) but if you can gather enough people it's very good!
you might want to wait a little tough since an upgraded port of the wii version is in the work
Half Minute Hero - i made a huge post about this one
http://www.evilbore.com/forum/index.php?topic=32323.0anyway the short version is that the world is going to explode in 30 seconds so you quickly have to level up and defeat the big bad before everything assplode! of course if every level lasted only 30 seconds the game would be over in an istant so when in town you get the chance to pay the time goddess a fee so she can reset the clock,the catch is the more time you reset,the bigger the amount of money you have to pay so you still need to be quick,the game is quite humorous and each stage feature different gimmick (it even has achievements!)
it's a pretty original and awesome game!
Prinny: Can i be the hero - it's disgaea meets ghost & goblins! it has disgaea humor and g&g tight gameplay,in short it's awesome
Patapon - patapon it's another pretty original game,basicaly you control a tribe of weird eyeball guys called patapon,but you don't issue commands normaly,instead each button of your PSP count as a drum and you issue command by playing certain tune at rhytm (so for example the "go forward tune" is "X,X,X,O") the better your rhytm,the better they fight,there are also small rpg elements as you can improve your patapon with material you find around and give them better equipment
patapon got a sequel but if you ask me,it really doesn't add much and unlike the original it's somewhat grindy
patapon is also getting a third game so maybe you might want to wait
Metal Gear Solid: Peace Walker - it's metal gear... it now features slightly rpg element and multiplayer,we have a thread about it so i guess it would be easier to just read that
Metal Gear Acid 2 - when most people think about card game they tend to think about magic the gathering but this would probably be better described as "stealth 2-unit x-com with random commands draw from a pool of cards" i never finished it but it was okay
Gurumin - action rpg by falcom,it's pretty reminiscent of ye olde games like alundra and brave fencer musashi,it even has the obligatory ruin dungeon!
Patchwork Heroes - quite similiar to qix but with a pretty original spin,giant airships are attacking the city so our unnamed hero decide to stop them... with a saw! basicaly you have to cut the airships removing pieces from them while dodging missiles and robot until the airship stop working
to be fair i think it's too short and simple to be worth a buy but certainly the whole theme and style is original enough to be worth a mention
what did i do to deserve this this one is quite weird too... you are an evil overlord and you have to defend yourself from those nasty hero! you do so by building yourself a nice dungeon,the entire place is divided in a grid and breaking certain block will spawn low level slimes... the slimes aren't much of a challenge but they make block which can spawns better creature like lizard and bugs and also provide food,ultimately you have to spawn enough monster to kill the heroes who try to infiltrate the dungeon
again this is pretty short and sometimes it feel like no matter what you do,you are destined to fail but like with patchwork heroes i think it's worth of a mention
Hammerin Hero - a 2.5D sidescroller,this one come from irem... it's short but fun while last,prinny is definitely better tough if you have to choice
Yu-Gi-Oh Tag Force 4 - i love card game and this is the only card game you will ever be able to scraps on a console or portable,i would hold it tough because a tag force 5 has already been announced
which obviously is going to have more cards and stuff
mmm... what else,there are quite a lot of rpg but they are quite average (like crimson gem saga

) i guess there is class of heroes if you like dungeon crawlers?
there are also tons of ports and remake,if you have never played disgaea this is a good time to do so
riviera is also another decent game that got ported from the gba