Bodybuilding.com

Bodybuilding.com has great tools to keep track of your weight lifting workouts. They also have a variety of ready to go workout plans that you can choose from. Right now I'm doing the 12 week massive muscle program. The only drawback I've seen to tracking your workouts on the website is that it's impossible to enter cardio workouts without messing up your weight lifting stats. Overall though, the website is a great tool, so long as you don't mind the barrage of ads for supplements and the like.