If you've never read the book Predictably Irrational there is an interesting chapter regarding a professor who performed an experiment with deadlines for his 3 papers due in the semester.

[simplified]

Class 1: Set your own deadlines Class 2: Strict deadlines from the professor Class 3: No deadlines

Guess who performed best? Strict deadlines.

[edit]

Also, I highly recommend the book : http://www.predictablyirrational.com/