Nice dumbell conditioning routines -- I'm pretty convinced that with nothing more than a dumbell and some plates one can create an excellent conditioning and fitness program very cheaply.
Hoover-Ball! Goes like this: you take a 6# medecine ball, 4-6 people, and a volleyball net. Throw the ball over the net, the other team has to catch it, and throw it right back. Fun, and physically demanding. Via CrossFit journal (in a round-about way)
The basic idea of the workout is that you perform 10 sets of 10 reps of pushups. Each set of ten utilizes a variation on on standard pushup to work different muscle groups. This also uses rings.