My good buddy Scrapper recently posted this John Hackleman workout (in case you're wondering, John Hackleman is the trainer of UFC Light Heavyweight Champion Chuck Liddell) on the S&C forum over at mma.tv. It consists of only two exercises - Dive Bombers and Burpees. It looks simple, but it is absolutely brutal...

-20 Burpees
-1 Dive Bombers
-19 Burpees
-2 Dive Bombers
-18 Burpees
-3 Dive Bombers

continue like this until you get to:

-1 Burpee
-20 Dive Bombers

The great thing about this workout is that you can so easily modify it! You at the point that the above is "easy?" Do like Scrapper did, and instead of rest for 30 seconds, sprint 20 yards. Or you could add 5 Chins or Pullups after the Dive Bombers. Or add a Jump Squat to the end of the Burpee. Or worse yet, instead of Burpees, do 8-Count Bodybuilders. If you're a real sicko, do it while wearing a weight vest...

The possibilities for such a workout are endless.