SeaMonkey

Blogzilla
A weblog covering news, tips and hacks.
http://www.deftone.com/blogzilla/

edafe Mozilla
Help and information about how to perform common functions in Mozilla.
http://www.edafe.org/mozilla/

Gemal.dk - Mozilla
Provides some links to articles about Mozilla and information about building and testing Mozilla.
http://gemal.dk/mozilla/

Gunnar's Mozilla Help Site
Offers help for and information on Mozilla with a FAQ section as well as image-heavy How-To's about installing and configuring Mozilla browsers.
http://mozilla.gunnars.net/

Hidden Mozilla Prefs
Description of some hidden prefs to customize Mozilla, also has information on customizations to the UI and content display.
http://www.geocities.com/pratiksolanki/

Keyboard Help for Mozilla
List of keyboard shortcuts.
http://www.squarefree.com/turing/mozilla/keyboard-help/

MozBackup
A freeware Windows utility for backing up Firefox, Thunderbird and Suite user data.
http://mozbackup.jasnapaka.com/

mozdev.org
Center for development projects based on the open source Mozilla project.
http://www.mozdev.org

Mozilla Icon Packs
A collection of icons packs for Firefox and Mozilla browsers.
http://iconpacks.mozdev.org

Mozilla Preferences list
A list of Mozilla User Preferences.
http://preferential.mozdev.org/preferences.html

Mozilla.org: Bugzilla
The Mozilla bug database. Search for reported bugs, and report new ones for the Mozilla browser suite and its associated components.
https://bugzilla.mozilla.org/

MozTips
Tips and Tricks for Mozilla.
http://www.moztips.com/

Blogzilla
Atom feed listing the latest articles and information posted at Blogzilla, a weblog contianing news, tips, links, and hacks related to the Mozilla project. [Atom]
http://www.deftone.com/blogzilla/atom.xml

Jacob's Mozilla Tips - RSS
Latest information and updates to the site via RSS. [RSS]
http://www.livejournal.com/users/jacob667/data/rss/

MozTips Reloaded
Tips and tricks for Mozilla with news items and user questions. [RSS]
http://www.moztips.com/rss_simple.php