gpsp - 3DS Port
gameplaySP (gpSP for short) is a GBA emulator written completely from scratch. It is still pretty young (only having started a 3 months prior to the first release) and thus rather immature, but it does a decent job of playing a number of games, and is being improved upon somewhat regularly.
It is currently somewhat minimalistic, in the sourcecode, presentation, and features. Its number one focus is to deliver a GBA gaming experience in the most playable way that PSP can manage, with frills being secondary (although still a consideration, at least for some of them).