What are your favorite MySQL replication filtering rules?

As I wrote a few days ago, I’m writing the replication chapter for the second edition of High Performance MySQL. I’m writing about replication filtering rules right now, and I thought it would be good to get input on this. If you have favorite replication filtering tricks you’d like to share, or tasks that always frustrate and/or confuse you, please post them in the comments. I’m making a section that shows how to accomplish common filtering and rewriting needs, such as preventing GRANT statements from replicating to the slaves.

Thanks very much! I hope the community involvement will make this book more useful for everyone.