Steps!

Along with jogging, I've been doing steps a couple of times a week.  It looks insane (I go up and down one step), but it is a killer cardio workout.  It's also fairly addictive -- I started at 300 and am up to 1,000 at a time, which takes about 30 minutes.  I also "run" about 30 stairs out of every 100.  Feels pretty darn good...