I have been playing this game since it first came out and have made many different characters.
A couple of feats that would be more for fun and to help round out multiclassed characters that i would love to see in the game would be the following:
Zen Archery - requirements: bab +3, wis 13+; use wis bonus instead of dex bonus for hitting enemies with ranged attacks.
Able Learner - learn non class skills as if they were class skills
I believe these two feats would help to open up the possibilities for some pretty amazing non traditional (maybe even functional) builds.
Thats my two cp, thanks for listening
Laquido