Rat Clubs:

Rat Fanciers of the Lakes (RFL) 
Michigan based rat club.

Northern Illinois Rat Organization (NIRO)
Illinois based rat club.

North American Rat Registry (NARR)
Online pedigree and health database (worth a look!).

Useful Information:

Breeder's Assistant
A pedigree program and a lifesaver.  No breeder should be with out it.

Fancy Rat Wiki
A wiki site with information on colors, markings and types of rats in the fancy.  The site includes pictures and genetic descriptions.

Rat Health Care & Information
A great resource for everything having to do with rats.  Also has wonderful comparison pictures for UK and US varieties as well as some of the newer varieties, such as Burmese and the BE colors.

Rat Health Guide
A wonderful resource for looking up symptoms and maintaining healthy rats.

Kim's Ark Rat Rescue
Not only do they provide forever homes for hundreds of rats, but they also have an online store then sells all kinds of useful items, including Harlan lab blocks and hammocks.

Animal Medical Center of Wyoming
Dr. Vincent is great with rats and have done so much for my kiddos.
AMC is very knowledgeable and indispensable.
Located at:  2330 44th Street Southwest, Wyoming, MI 49519, 616.531.7387

Cages:

Martin's Cages
Absolutely 100% the best there is.
Only cages that I use.