Get thee to a Sally Beauty Supply and pick up some Ion Repair Solutions Hair Reconstructor or Ion Effective Care Intensive Therapy, especially if you color your hair. They've worked wonders for me, and it only takes a little bit to make a lot of difference.
If you can afford a bit of a splurge ($10 bucks a bottle,) I recommend the David Babaii for WildAid Hydrating Shampoo- it's sulfate, paraben and petroleum free, lathers well and smells divine. If you're on a serious budget, Trader Joe's makes damn good sulfate free shampoos and they're dead cheap- under 3 bucks a bottle!