SlorgNet on 12 October 2009
I've had good luck with Handbrake -- it's open source and converts plenty of file formats into PSP-compatible MP4s (it comes with a bunch of preset options, just click on the PSP tag and start converting). One hint though: every now and then, the resulting video won't play due to size requirements, i.e. you have to shrink the vertical resolution down to 208. (Rare, but happens.)
