Portals are quite popular on PSP systems. They utilize the system's internet browser to allow easy access to internet applications, such as mail clients and online messengers. The latest takes the design of Apple's popular iPhone, and attempts to transplant it to the PSP. While it certainly looks sleek, the vertical alignment makes the system awkward. Still, easy to follow instructions and a great self-installer makes this one of the better portals to pursue.
Check it out here.
Engadget
TUAW