Over at the QJ Forums, kozine has released a homebrew flashing app for the PSP called Aqua-set v1.00A. It's a flashmod for 1.50 firmware PSPs. Currently in Alpha version, it's best to treat the app as a "proof of concept". Nothing much going on in the app right now, but you can do the following:

* Change Wallpapers
* Change Font
* Change Gameboot
* Change Bootsound

Kozine hopes to add a theme and custom firmware installer to the app. Don't forget to drop kozine a note if you have suggestions for the Alpha 2 or beta release.