1. Smart moms 
https://www.babysittingcoop.com/index.php?page=60
login as
member1@gmail.com, pw: member1
member2@gmail.com, pw: member2
member3@gmail.com, pw: member3

Pros: Very nice guy who runs it, will help us. I will forward my emails with him to you.
Cons: Not super-intuitive, but will work with our system w/out too much signal to noise. Not auto-notices to users, though Gary might be able to fix that.

2. The babysitters exchange
http://www.babysitterexchange.com/
bootsy.boutwell@gmail.com, exchange1
mike@equatorial.tv, babysitters1

Pros: Very customizable, reasonably intuitive (but not great)
Cons: Too many options.

3. Swap exchange
Awaiting evaluation login info
http://www.integratisinc.com/swapkeeper.html
check out the video demo link

Pros: Easiest, simplest interface
Cons: Software based, not web-based. Doesn't calculate number of points (I think, haven't found a way yet; customer service is not responsive.)

4.  Helping Hero
Helpinghero.com
Pros: Potentially  nice interface
Cons: Seems very crashy. Terrible calendar.