A new feature added not too long ago by Runkeeper is setting fitness goals. You can set distance goals, a goal for a race or a weight goal. Your progess gets posted in a graph on your profile.
It's a pretty nice feature. So far I have two goals: drop 5 kg by September 1 (4 kg now) and run a total of 800 km between now and the end of the year (which I just set today). Will be interesting tracking the progress of that goal.
Really enjoying using Runkeeper. Being the number junkie that I am, I think it's another little thing that's made my return to running more interesting.