http://www.guinealynx.info/guinealynx
Great information on general care, as well as medical issues you may run into with your cavy. THere is also a free forum with some very knowledgable people around to answer ANY questions.
http://www.oginet.com/pgurney/index.html
Peter Gurney's site, also a good site for medical issues.
http://www.cavycages.com/
Nice, inexpensive cage ideas.
http://www.cavyspirit.com/
a
guinea pig rescue out of CA, the page also has a lot of GREAT information on care too.
http://www.cavyspirit.com/sexing.htm
Part of the page mentioned above, great sexing page for pigs as young as 12 hours old. I found this to be the best page to help sex guinea pigs.
http://cavyrescue.com/
a nationwide search for
guinea pig rescues and adoptables.