if your already doing - EZ bar curl
Incline offset curl
I wouldn't bother doing anything else, thats more than enough. I have no idea what an incline offset curl is though.
The bicep is only a small muscle and doesn't require a multitude of different exercises. your better off doing a little more frequently than a lot less frequently.
I'd say my biceps/arms in general are pretty well developed and I don't think I've ever done more than 3 exercises a session.