I am by far no expert judge, but I did want to put together a little one stop shop for all things judging. For the most part there is some reading and pallet development you have to do on your own. But a great place to start if you are remotly interested in judging or evaluating beer is the BJCP website.This is already pretty much your one source for all judging info and testing, it also has a lot of info on competitions coming up and who to contact. Aside from that though, I wanted to provide a few more links and some real good books that will help you understand how to evaluate beer. I also am going to dedicate another page in here to how to doctor beer and help develop your pallet for tasting and evaluating beer

Books

Chances are that if you are interested in judging homebrew competitions, you are a brewer of some sort and probably have some key homebrewing books like the Brewmasters bible, The Complete Joy of Homebrewing, and How to Brew. If you don’t have how to brew, you must get that one because in my opinion it is the best book out there for brewing technique. But there are a few others that I found essential in working towards my certification. One of the books was Designing Great Beers. This book will describe all the major styles and the ingredients that go in them. It also give you some history into the styles and does well for describing the flavor and aroma profiles of the styles. Another book that is a must have is Evaluating Beer. This book is a great tool for all things judging. It has troubleshooting guides, flavor and aroma descriptions, how to develop your senses needed for judging. Some of this book is very technical, but and quite frankly is over my head, but I still found it an indispensable read for the exam. Plus, this book is where I got my information on doctoring beer for both aroma only, and flavor labs. On top of that there are little tricks to make grain tasters and hop teas.
Probably the newest and easiest to read books out there dedicated to the subject of beer tasting and evaluation is Tasting Beer by Randy Mosher. This is simply a great book and explains in easy to understand terms, how properly evaluate beer for not only formal tasting, but overall beer enjoyment. This book is exactly what I have been waiting for. This is my most recommended book for someone interested in judging.

Below are some links You may enjoy as well.

The Beer Judge Certification Program (BJCP)
Here is a brewing network podcast dealing with the BJCP and judging.
Podcast 1

Beertown.org
HBD.org