Ratchet and Clank is a platformer with shooting elements. Its great. Picked it up today!
If you are a shooter fan, Medal of Honor: Heroes is a decent FPS. 32 online multiplayer.
Also, fantastic thrid person shooter is Syphon Filter: Dark Mirror and Syphon Filter: Logan's Shadow.
Dark Mirror is only $20. Rainbow Six is the 360 game.... with bad graphics and a tricky control scheme.