If you need a little bump to remind you to get off your ass and get something done, then get yourself A Round Tuit. They are free and can sometimes help give you that boost you need. Also, if you have a friend who is behind on a deadline, think about e-mailing him one as well.
Now if someone e-mails you A Round Tuit, then you can get back at the sending party by sending them A Square Tuit.
After stumbling upon the question "what does your writing workflow look like?" on the 