http://dl.qj.net/Super-Nintendo-SNES...-DS-/catid/236
Good place to go for DS/PSP homebrew. The SNES DS section doesn't get updated very much since a lot of games have trouble running. That, and resolution issues.
The last time I used an SNES emulator on DS, SNEmulDS was the best version with a pretty good interface, some different settings, and a pretty smooth framerate. Some games ran better than others, though.