I like this: in an attempt to shame himself into losing weight, Kerry Buckley has a Big Visible Belly graph showing on his blog, which shows his fluctuation around his ideal weight - over and it records in red and under it shows in green.
This use of the blog to expose some aspect of yourself to the audience and thus force action got me thinking. What else could you use it for? I would probably like to record my running, with a weekly target. But anything you procrastinate over would be a contender - you could go for study hours, progress through Remembrance of Things Past, number of alcohol units consumed (depending on whether you wanted to drink more or less), blog posts even.
I think the visual element is important - you get an instant nudge if it's largely red. So is the pressure from the audience - this only needs to be perceived, none of your audience actually needs to care or comment, but the fact that it is public is sufficient. Another Facebook app maybe?