Matthew Phillips wrote a piece on how to backup your Mac using a free utility called RsyncX. The article goes through different backup scenarios in detail and will be useful for anyone who wants to backup their Mac.
RsyncX is downloadable from VersionTracker.
More info on RsyncX and its author Kevin Boyd is available here.
If you are looking at free products you might checkout this tutorial. It shows how to create a bootable version of your drive that you can just bring up on another computer if necessary.