Hi Cormac,
Here's one I used to use a lot:
http://weird.ie/files/backup.phps
You can cron it to run every night, best to use nice also to stop gzip murdering the server.
One thing to note, if you have a directory you want to backup as 1 tar.gz then put in "/path/to/folder/". If you want to backup files or folders seperately within a directory then appened a * after the last slash. There's a few examples in the file.
I also used to have it scp the files to another box when it was done. Rather handy, but very simple.
Paul