PSP Unbricker PANDORA Installer [h33t][migel]

Reasons To Use Custom Firmware:
Full screen movies work on custom firmware

Homebrew games, many of which are really fun and well made (Super Mario War, PSP Dungeon)

Ports of classic open-source games (such as Quake and Doom II)
Custom backgrounds, waves, and fonts, icons

Unlocked 333mhz mode allowing you to play all PSP games at smoother speeds

Plugins, such as screenshot support and in-game music players

Recovery Menu, preventing you from causing any damage to your PSP's internal flash

Removes the restrictions Sony puts in place on it's PS1 emulation engine, opening the door to a huge library of PS1 titles

Allows you to drop the CPU speed of the PSP, saving battery life in games that don't require much processor power

Allows you to use the 4th brightness level

You can change the region of your PSP, opening up the ability to watch foreign films and access japan-specific features

You can lock your PSP, preventing people from accessing it without knowing a specialized keystroke

Keyboard support

Custom Firmware does not limit your ability to play new games or special beta games

You can control your PC or Mac from your PSP using VNC

You can run other PSP firmwares from your memory stick using Devhook, rendering your PSP effectively brick-proof

Thanks to the Recovery Menu, custom firmware is significantly safer than Sony's official firmware

You can use a homebrew chat program to talk to all major chat networks without having to go through the web browser

You can use your japanese GPS system with a homebrew map reader to get GPS access in the states

You get all of the features of Sony's firmwares... there is no downside.

More info << Click

NOTE:
I dont try (i dont have PSP).