NervOS is a shell application for PSP.

Features:

Calculator
Web Browser (sceKernelExitGame is patched on it so it returns to NervOS
after the user quit it)
Sony OSK for text input
Ability to skip tracks (after loading a playlist)
Ogg Support
Playlist reader (m3u)
File Browser: ability to delete files/folders.
File Browser: ability to rename files/folders.
File Browser: ability to copy files/folders.
File Browser: ability to make folders.
File Browser: displays file size after file name.
File Browser: sorts alphabetically folders and files and folders are
displayed before files.
File Browser: detects more 14 file types.
When entering Load Music, the music only stops after you choose a new
one.
Customizable font.
Icon0.png
Remove highlight bars.
Removed “..” and “.” From the file browser.
Fixed a bug in the task manager.
Internal Core changes
Fixed bug in the Image Viewer.
Fixed bug in the clock system

http://forums.qj.net/showthread.php?t=138986