Actually the homebrew scene for the psp is RIDICULOUS. Most of the time homebrew makes up a very small percentage of console owners, but in the PSP's case it's the exact opposite.
You have to get one for the DS too, so it's a moot point. You just also have to drop money on an adapter.
So what you're saying is the only emulator out and working is the NES one.
PSP has SCUMM, SNES, Genesis, n64, PSX, MAME among many many others.
Not to mention wifi radio, gps, texting, portable tv, and awesome movie/tv show/music usage.
Seriously, you've lost this one. The PSP's homebrew scene is much larger, better, and more fleshed out than the DS'. I've owned BOTH handhelds and still like the PSP more (I wish mine didn't have 300 dead pixels when I sold it, but that's what happens when you let people use it and they drop it 500 times. Cocksuckers.), if only because of the homebrew, though I like the library quite a bit more also (aside from Megaman ZX and the Castlevania series.)
EDIT: Oh yeah, and this thread's already godwin'd /_\