Guwange is one of the best Shooters out there and plays sensational on FBA320. Just be careful with which version you get, some of the versions freeze upon exiting the game.
Also DonPachi if you don't already have it.
Obviously you also have your CPS2 anmd Neo Geo games... But I prefer the native emulators for them.
NES, Master System, Lynx, Mega Drive, Mega CD, SNES, 3DO, Playstation, Saturn, N64, PS2, Dreamcast, XBOX, X360, PS3, Wii..... And best of all... A320.