Reptile
Welcome to Reptile!
Reptile is an easy to use utility that will monitor your MySQL replication, so you can forget about it and focus on the good stuff. For a little more info, check out the features or check out the RDoc.
Reptile will hopefully work for you, but I would bet (sigh) that it is really just a starting place. Take a look at the code, and hopefully you can find something that will work for you.