If you want a full body work out from biking, try trials riding. Pushing the bike around really works out the arms, back, and shoulders.

Or, you can augment your riding with calistenics or lifting. I personally lift 2-3 times per week. The last couple weekends, I rode to the river swam for a while, then rode back (the weather's really hot right now and the water's probably up to 55 degrees here...perfect). That was pretty good, but I don't plan on making a regular thing out of it due to time and the impending end of summer.