In gmail, I automatically label all of the incoming TextMate messages as TextMate. But further I have gmail star all of the messages that mention Python, Latex, or SQL since those are the messages I'm most interested in following. This makes it really easy to find the interesting stuff and mark the rest as read when I get a few days behind.
I automatically label apply the label "TextMate" to all messages incoming from "lists.macromates.com". Additionally, I archive these messages so they stay out of my inbox. Happily, archived messages don't lose their read/unread/flagged status, so you get a count of unread messages under the label.
Now that I read Brad's email, I'm going to go add some more rules to flag topics I'm interested in!