How to Get Chlorine and Other Gross Stuff Out of Your Hair
Chlorine is really bad for your hair. (Salt water isn't so great for it, either.) The most important thing to do is to wet your hair with non-chlorinated water before going into the pool. Your hair is porous, so the water fills up the cuticle, making it difficult for anything else to get trapped in there. If you really want to go the extra mile you can use hair oil or a swim cap. If you ask the US Olympic swim team, swimming caps are so in right now.
If you're really anal about not getting any chlorine in your hair, but not feeling the swim caps, use hair oil as a protectant before going into the water.