This is an excellent resource if you have a cat or you are planning to become a cat owner. This site has information on cat behavior and training, cat breeds, and mating. An overall informative site.
This is an excellent site if you have or want an aquarium. They have tons of great articles with helpful tips and advice. If the articles don't resolve the question, you can always use the forum to get advice from other aquarium owners.
I use catster and I really love it. I didn't realize they have dogster as well. I have cats, but this site should be great for dog lover's. I have gotten a lot out of the site for cats, and both sites have identical layouts.
This site has a lot of valuable information about various cat breeds. This is also a good place to browse cute cat pictures. The site contains helpful articles and a cat adoption search. It is basically everything you need regarding cats.