Basically, you make a weekly schedule with hourly increments. Then you schedule time for sleep, free time, recreation, socializing, exercising, etc. You don't schedule any work. Then whenever you get at least an half hour of uninterrupted work done, you shade in your schedule. Then each week you tally your hours worked.
The unschedule works to motivate you because you mark off time for what the author calls "guilt-free play" and because you can see quantifiable progress. It's easy to kid yourself that you're doing serious work when you're just surfing or whatever. If you only shade in actual uninterrupted work, you'll increase your productivity. There's a lot more psychology involved behind the system but those are the basics. Check out the reviews on Amazon. I don't think you'll be disappointed.
I've never been able to stick to regular schedules but the unschedule turns the concept on its head. When you look at week's work, it gives you a certain satisfaction and you actually feel bad if you don't get a good amount of work in.