I came across an interesting post from Mark Arend today whichi nicely lists out all the Moss Timer Jobs with a description of what they do along with some assembly info, catch it here:
http://blogs.msdn.com/markarend/archive/2008/09/06/list-of-moss-timer-jobs.aspx
It was posted a while ago. But hey this way I'll find it again easily.
IainW