How to Start a Babysitting Co-op

How many of you are participants in a babysitting co-op?  If you are not (or have never heard of one) are you interested in starting one in your neighborhood.  Below is the advice of some moms who have found babysitting co-ops to be invaluable.

Amy:

I've done 2 different types of babysitting swaps/co-ops. Both might not be considered a co-op because it's not a big group – but regardless, I love it and it works!

I have one friend that we swap kids/errands – she will watch the four kids while I...