I'm really liking Seamonkey lately! I decided to try it when Firefox and Thunderbird stopped communicating properly with each other. Clicking on a link in Thunderbird used to automatically open Firefox and go to the URL in the email, but just quit working one day. Clicking on an e-mail address in Firefox used to open Thunderbird and automatically start a new composition window addressed to the recipient in the link. That too just stopped working one day.
Seamonkey is still a Mozilla project, and having really enjoyed FF and T-Bird for so long I thought I should look at Mozilla's other stuff before exploring totally unfamiliar new browsers. I'm really glad I did! It seems a little faster than Firefox, has most of the add-on compatibility, and of course, perfect integration between the browser, the e-mail client, and the additional goodies (IRC chat, HTML editor). It "feels like" an older and slightly faster version of Firefox and Thunderbird in a nice all-in-one "Internet suite." I really like it! And Seamonkey has been the default browser/email client for several releases of Puppy Linux because it's so easy on resources, yet about as fully-featured as it's separate cousins from Mozilla.