SeaMonkey - More than a Web Browser
I actually first discovered SeaMonkey many years ago when trying out the many versions of Puppy Linux, where SeaMonkey was sometimes included as the default "web browser". Of course, if I had actually paid enough attention, I would have realised it was labeled as an "all-in-one internet application suite". But nevertheless, it looked and behaved like Firefox so I assumed it was just an off-shoot of that software.
Recently though, I once again installed SeaMonkey out of curiosity and found it was much more. In fact, it has even been my primary web browser (after using Chromium primarily for some time, although I still use that browser for it's inbuilt Web Developer Tools), primary mail client and my primary IRC client (when I use it) for some months now.