Following up residents' assignments

Haven't you found yourself giving assignments to residents or coworkers through email and realize weeks or months latter that these assignments were not carried out? If so, how do you deal with them?
I used to do it with my "To do" list but, on one hand, this made my "To do" list very long and on the other one, running down every day your "To do" list is not only time consuming, but many times you don't do it at all.

How can we keep an uncluttered "To do" list and at the same time, be reminded timely about the tasks you must follow up?

I have found "Deferred Sender" at http://www.deferredsender.com/ a very useful tool. Deferred Sender is a free service that allows you to schedule emails from any email application or website to be sent in the future.

The way I make it work for me is that every time I send out a task through my email, I just copy it to "deferred@deferredsender.com" with my email and the date on which I want to be reminded about the task. On that date, it will enter my email box and sit at the top of the unread mail to remind me about the task.

You can find more information at http://deferredsender.com/help