Review for Silvermel by 4slam
Rated 4 out of 5 stars
Very elegant -- I'm using it in T'bird. Held back on the 5th star because:
1. The star indicating new mail in POP accounts is barely discernible.
2. Feeds and IMAP account images have no indication of new items.
3. There is no distinction between mail folders and custom search folders, both have the same image.
To create your own collections, you must have a Mozilla Add-ons account.