Sony PSP v1.50 swap hack
Here is the current best way to play homebrew games. (download rar or from its mirrors) This really makes the PSP very cool and opens a lot of possibilities!
Note from a poster at SlashDot:

Re:Article Text (Score:5, Informative)
by sjf (3790) on Wednesday June 15, @11:22AM (#12823705)
(http://www.cogco.u-net.com/)
To make things a bit easier, I've found that you only need to create the MS1 stick once. That is, once you have the special EBOOT.PBP on the first memory stick, you don't need to recreate it every time you change the EBOOT.PBP on MS2. Obviously, the file on MS1 will report the wrong name, but whatever is on MS2 still boots. Tested with the PCEngine, GB emulator and the SNES emulator.

And here's an UMD Dumping utility for no reason.