Review for Flexible Identity by Bill Nickerson
Rated 4 out of 5 stars
This is a great addon and works well. The only thing I don't like is that it doesn't have a menu entry under tools. Heading to Add-Ons and then selecting Options is the only way I've found to get to the dialog.
A nice feature would be to create or add to a profile by right clicking on an email address.
To create your own collections, you must have a Mozilla Add-ons account.