I use Fitocracy mainly to track my running, but also for some other workouts here and there. I just like having the historical data of how far and how fast I'm going each run (in fact I wrote a simple API to get at my run info out of Fitocracy: https://github.com/dorkrawk/unofficial-fitocracy-runs-api ). When I'm training for a race I have an idea of what I need to be doing each week so it's nice to have that data in one place. I also appreciate seeing what my friends are doing because it acts as a motivator for me to not slack off.