the POP gameboot isn't a custom gameboot.....its been ripped for the POPiso
custom gameboot are ones created by users, not by sony or game developers..
here is a list of the custom gameboots made so far.....
Thanks to GmDude66 for makin the list.
Custom Gameboot List: Azumanga Daioh - straylightrun
Big Brother - muratcan
Nintendo DS - DarkStone
Spiderman 3 - DarkStone
Final Fantasy - DarkStone
X-Box 360 - DarkStone
Another Final Fantasy - DarkStone
Mystical X - SSChevy2001
Birdhouse Skate Skit (gorey) - mrdlouisd
If you would like to preview any of these gameboots before you flash them to you PSP, please install this PMF codec and open the file with Windows Media Player (or another compatible application):
http://www.psp-hacks.com/download.php?id=536