those gay ellipticals that have the arm movement involved. they are gay, but they do loosen you up pretty good. I like to start at no incline go all the way up and all the way down over 10 minutes. just to loosen up my whole back. works pretty well.
yoga, also gay, also loosens you up Do I feel retarded doing it? yup, do I care more about final goals than feeling retarded, absolutely.
swimming loosens you up. only kind of gay. I suggest freestyle, backstroke and breastroke in alternation... fly won't help you feel better.
Something I've foudn to be motivating, go play some team sport with people in not as good as shape as you (assuming your in really good shape) keeps you moving and feeling good loosens you up, soccer, basketball, ultimate frisbee. but if your really sore, and playing against people faster thann you...... it turns into another training day. which won't help you any. (Like when I play with 5 members of the University of Michigan team.... its my sprint day)