SuccessHK have posted news of a new accessory for the PSP, heres the details:
Product Features of Home AV Arts Organisation
Mega Sub-Woofer
Vertical Stand function, the stand is adjustable
Charging function
Retractable Speaker
2 colors available: White / Black
More Description of Home AV Arts Organisation
This item has 4-Speaker built-in with power amplifier & BBE system function which can output quality sound effect. Hidden tray can store up to 12 UMD. Wireless remote control function allows you to play/forward/backward easily.