I agree with the others, stretch, stretch, stretch. Ibuprofen. A hot bath or heating pad can help.
But for me, I've found that pushing myself through another (different, perhaps less strenuous) workout helps the most. It gets oxygen pumping back into your muscles and works wonders. If you have sore legs...walk for a little awhile. If you have sore arms, try a few gentle arm lifts without weight while stretching. Just move the muscles around again as much as you can without hurting them more. The goal is to just get the blood flowing well, not really building muscle or anything so don't push it too hard. After doing the same workout a couple times the DOMS will improve too so don't worry.