There are many plugins for browsers to enhance standard tabs. Many of them are quite similar so here is a selection of them.
Many of these are in the sandbox and require you to login. Here is a temporary login:
User: moc.liamg|sbatderit#moc.liamg|sbatderit
Password: larsen
CTRL-Tab
•Works like alt-tab. Shows a preview of the site while you tab through them.
Plugin: https://addons.mozilla.org/en-US/firefox/addon/2134
LinkBunch
•Creates a remote link on linkbunch.ch with links to a group of sites. It will open them individually or in tabs.
Plugin: https://addons.mozilla.org/en-US/firefox/addon/6496
Separate Tabs
•Automatically arranges tabs by their domain name.
Plugin: https://addons.mozilla.org/en-US/firefox/addon/4913
Tab Cloud
•In very early development stages. It's suppose to automatically select keywords and create tags which limit the displayed tabs. Currently it only works with Japanese pages.
Plugin: http://tabcloud.mozdev.org/installation.html
Tab Kit
•Offers many options for tweaking how tabs work. It also allows for grouping based on domain name or parent/child relationships. All of the specifics can be found here: http://jomel.me.uk/software/firefox/tabkit/
Plugin: https://addons.mozilla.org/en-US/firefox/addon/5447
Tabsearch
•Searches tabs by headers and displays tabs that fit the search. It would be more useful if it searched the contents of the tabs as well.
Plugin: https://addons.mozilla.org/en-US/firefox/addon/6332
Inactive Tabs Closer
•Darkens color of tabs when they have not been used. Allows you to close all unused tabs with a click of a button.
Plugin: https://addons.mozilla.org/en-US/firefox/addon/5049
Taboo
•Allows you to save tabs, including user data, to access later. When you view the list of Taboos you get a preview of the page and you can search by header.
Plugin: https://addons.mozilla.org/en-US/firefox/addon/5756
Fox Pager
•Shows thumbnail previews of opened tabs. This plugin is a lot like Shiira's pagedock.
Plugin: https://addons.mozilla.org/en-US/firefox/addon/2174
Next Tab
•There are many similar plugins to this one. This will open your tab to the immediate right of the parent tab. This allows for haphazard organization.
Plugin: https://addons.mozilla.org/en-US/firefox/addon/5484
Firefox Journal
•Creates a homepage full of the user's recent web activity, a "Top Sites" visited section as well as a search section.
Plugin: https://addons.mozilla.org/en-US/firefox/addon/6744
Sogudi
•A Safari plugin for easy searching
