Screentoaster has been around for a couple of years now, but I thought a reminder of this easy to use free tool was in order. Give it a try and add lessons or presentations to your site in minutes.
Jing is the more widely used and a little more complicated screencasting tool. If you are more tech saavy you probably would be better off using Jing. If you need a screencast quickly and easily, then Screentoaster would be your best bet.