Check out some of the things that LinkedIn does to get me to edit my profile. First, after logging in they present me with this button.
Then, after I’ve clicked and can edit my profile, it gives me this clever little statistic which makes it fun to update my profile.
Then, when you’re actually filling out your profile, you can choose between a simple view, and a more detailed view. It even updates the preview image whenever you click any of the check marks. Brilliant.