total noob question

Traditionally, I've programmed for IE (stop the booing).  I went where the 
money was, the shameless whore that I am.  Now, I have need to write for 
Firefox.  I found the links for the API, et al at the Mozilla site.  I was 
wondering if anyone could share any links to sites for more advanced 
development for when I get to that point.

Thanks.

Tim