At Dom's request - I'm here to tell you about X-Moto. First of all, X-Moto is an open source version of a game I played in 6th form called Elastomania. The premise is that you are motor cycle rider stuck in a 2 dimensional plane with alarming physics constraints. You can download X-Moto from the sourceforge web page. Its fun, although very difficult and frustrating. I'm currently up to level 18.
One of the best features of X-Moto is that it records the world records for each level. You can also download the replay of the world record and watch how it was done if you can't do a level.
So what I'm doing is porting X-Moto to PSP. Most of the librarys X-Moto uses have been ported to PSP, which makes things easy, so I have to write code to handle the different file system and screen size and inputs. I'm probably going to have to do some other optimisations to get it running fast enough. At the moment, I have the main menu working, and you can watch replays (I transfered some from my computer) although the replays are not quite full speed yet.
Go on, download it, give it a shot.