www.kayak.com is a good site, it compares all of those travel sites
also check the actual airlines websites, sometimes they do "internet specials" that won't show up on any of the travel sites.
I've found the cheapest airlines are South West and Air Tran, they seem to be really nice to their customers too
Air Tran is based out of Atlanta, so no matter where you're going, you stop off in Atlanta
anyway, check both kayak and the airlines websites
<EDIT> Ok didn't see you said honolulu, I'm pretty sure Air Tran doesn't go there, but still, heed my advice!
