Thunderbird way more useful as an IMAP client if you tell it to check all folders
I've been using Thunderbird as an IMAP client (tunnelling the IMAP connection through an SSH connection from the office to my home box, which runs the IMAP server) for a while now, except I've always been keeping mutt open in a separate SSH window to tell me when new messages arrive, because Thunderbird only ever seemed to check the current folder, and even then, not often enough.
One of my officemates told me last week that you can tell it to check all folders for new mail... here are the details. I made that change and now it's way more useful.