Remember that each time you put your muscles through strenous exercise, you actually damage them! Fortunately, they recover and come back even stronger. When exercise becomes too strenous, lactic acid is produced (the burning sensation you feel when you climb, for example). This is the body's protection system coming into action.
I suggest you give your legs a good rub down after training or competition (or get someone else to do it for you, perfect excuse for a nice massage ;D). Most cyclists don't know the value of proper massage.
I try and take a nice easy pedal the day after a heavy ride, just to get rid of any dormant lactic acid. Nothing hectic, just a nice slow pedal. It works for me. I've also acquired one of those electric pulse generators (the APS model). After a heavy ride, I take a hot bath and then use 'the machine' on my legs. The day after, pain is almost non-exsistant.
On the other side, I kinda like the feeling of slightly sore muscles ;D