Thanks for all the advice, everyone! I think I'm going to try doing super slow pushups and otherwise just do pushups whenever I remember to. i do do other kinds of upper body workouts as well (at Crossfit). I just wanted to find something that I can do on top of my regular workouts to sort of speed things along.
Leida--I'm definitely going to check out the 4-Hour Body. I strongly favor my right side as well, and it's become really noticeable and concerning lately. In fact, it's gotten so bad that sometimes only my right arm would be sore. That just means that my right side would keep getting stronger and my left side relatively weaker. This obviously can't go on.