Would love a pushup and situp app that uses the orientation sensor to count the pushups or situps that you do and log each work out. Maybe even have a program you can follow including the 60 sec timers in between sets, what days to do the sets, and maybe even have popups on the days to remind you to do your pushups on the days your are scheduled to work out.

Just some ideas... not saying they are great but maybe someone can run with it.