Spay USA: Nationwide network of over 900 affordable sterilization programs:
http://www.spayusa.org
Humane Society of the United States: "Myths and Facts about Spaying and Neutering":
http://www.hsus.org/ace/11823
Pets 911's Spay and Neuter Page, which includes referrals to local low-cost spay and neuter programs nationwide:
http://www.pets911.com/services/spayneuter/
Prevent A Little Coalition: Spay and Neuter campaign with lots of research and spay/neuter resources:
http://www.palc.org/
The Dog Hause: Six Common Excuses for Not Spaying or Neutering Pets:
http://www.doghause.com/neuter04.html
Feline Rescue: List of low and no-cost spay and neuter programs in the United States and Canada. For dogs, too!
http://www.felinerescue.net/speuter/resources.htm
Happy Pets: Another great list of low-cost and free spay and neuter programs in the United States.
http://happypets.addr.com/lost_cost_or_free_spay.htm
A great personal essay about one pet owner's decision to neuter:
http://personal.cfw.com/~dtratnac/neuter.htm
The Pet Center: Great source of information about the actual spay and neutering procedure (Warning: includes graphic surgical photos):
http://www.thepetcenter.com/sur/ Spayandneuter.htm
The Dog Owner's Guide: "Spay or Neuter Surgery: A Prescription for Better Canine Health"
http://www.canismajor.com/dog/spayneut.html
How to Love Your Dog: "Too Many Dogs", a great page that teaches children about spaying and neutering:
http://www.kidsanddogs.bravepages.com/toomanydgs.html
NetPets article "A List of Some of the Less Than Exciting Behaviors Associated with Unneutered Male Dogs":
http://www.netpets.org/dogs/reference/ info/behave.html
Friends of Animals: Order a spay or neuter certificate online!:
http://www.friendsofanimals.org/ spaying/cover.html