Mary found this page a week ago: one hundred push ups.
It's a simple workout, the standard pyramid where the sets decrease in number of reps as your muscles tire. The goal of the program is to work your way up for 6 weeks until you're able to do 100 consecutive push ups. It should take about 30 minutes a week initially, probably more like an hour a week at the end, and then you should be able to do 100 in a row.
Mary and I just started. We both tested at 20 push ups (I'm doing traditional, Mary is doing the "knee"), and we completed the workout Monday night, which was about 50 push ups in total. By the end, the workouts will result in 250 push ups.
I just think it'd be pretty macho to be able to drop and do 100. We'll see if it sticks. Check back in 6 weeks.