I keep trying to find ways to do it all triathlon fitness-wise: swim, bike, run | speed, tempo, endurance | strength, flexibility. My first attempt at multi-tasking my workouts was Burbathlon.
Then I came up with the Swim + Pushups workout.
And now my latest masterpiece madness creation... A WorkoutHack for Bike - doing Hill Repeats and Strength work with the bike. The premise is pretty simple, you use the bike as a weight to do strength exercises at the top of the hill after every climb. Now, the reps I show reflect not only my own strength and fitness level, but the weight of the bike. A commuter/hybrid or mountain bike is good for this (maybe with even fewer reps for bikes with suspension systems), but light road/racing bikes would require more reps. Adjust as needed.
Note: I am not a certified fitness profesional and all exercises should be performed at your own risk. Please consult a physician before undertaking a new fitness/exercise program.