The SNK Neo Geo Pocket Color

RACE! PSP is a Neo Geo Pocket and Pocket Color Emulator for the PSP. The latest version is 2.16

RACE PSP 2.16 Changelog:

Time Rewind feature: map ‘Special: Rewind’ to any PSP button in the Controls menu to enable. See documentation for more information
Save state format has changed: RACE! PSP will still read the older save state format, but loading will be slightly slower

Not a new feature, but the documentation now includes a section on how to have RACE! PSP load a BIOS ROM file (instead of using the customized hardcoded version)

Source: RACE! PSP Official site