Unobtrusive Javascript is Javascript that latches into a page without the need to mix javascript event handlers  and HTML.  Chris Heilmann has a good article about the “Seven rules of Unobtrusive JavaScript” – there is a short summary on his blog and an expanded version here.  If you are not familiar with unobtrusive javascript this is a good start, if you use it regularly and want to spread the gospel this is a good list to prepare for a presentation, so you should read it in any case.