I was just taling about pet insurance the other day with a friend as I've looked into it in the past. With the number of pets I had at the time it was too much per month for me to pay.
I did think of an alternative though for those of us who don't want to give our money to a pet insurance company. If you have the self control you could always set up a pet costs savings account and just put in what you can when you can. Even if it was just $20 a month it would help cover some of the cost for regular visits.
I've started saving for the adoption fee and initial vet costs for the kittens I plan on getting in November and am surprised by how much I've been able to squirrel away.