Gmail Finally Adds a ToDo list

It is called Tasks and is now available in Gmail Labs (click on the beaker icon next to Settings on the upper right hand corner of Gmail).

When you enable Tasks, it appears as a link in the left-hand column under Contacts. Click on the link and a box pops up.

Check it out here:
http://www.techcrunch.com/2008/12/08/gmail-finally-gets-a-to-do-list/