I use VPI and am very happy with it. I chose the superior plan that covers things way beyond emergencies - including prescriptions, vaccinations, boosters, neutering, flea and heartworm medication etc.
My baby already had an emergency this year, and I am so glad I had the insurance! I pay $50 a month but have already saved money (compared to if I did not have the insurance).
Getting reimbursed is very easy - just have to fax a form and the receipt over and the check comes in the mail.
Here is a link:
Veterinary Pet Insurance (VPI) - Dog Insurance, Cat Insurance, Pet Health Insurance