In the past we reported on earning 400 easy frequent flyer miles for completing WorldPerks University online quizzes, which consist of answering a few multiple choice questions about the Northwest Airlines frequent flyer program. If you haven't completed the quizzes yet, now is a great time to do so.
In addition, with the Delta/Northwest merger already in progress, you can earn 500 Delta miles for linking both your Delta and Northwest accounts together - then, turn right around and transfer those miles back to your Northwest account, fee free. The linking bonus runs through April 30.
These combined activities will net you 900 Northwest Miles. Not too shabby for 10 minutes of work!