Hazel is great for operating on files and folders, but it would also be good to have it work with the OS X Mail app as well. Apple's rules are great for filing and other processing but they operate on newly received messages. It would be great if Hazel could open up a mailbox file and perform a rule on it. For instance, I have a mailbox for all of my forum messages. I would like the messages that are over 2 weeks old deleted. I have similar needs for other mailboxes that I have. For instance if I don't read a message in my "Statements" folder after a week, I want to be alerted. The infrastructure is in Hazel to do this. It seems that you would just need to be able to read and write to the ".mbox" file format Apple uses.