Addons I have used or tried in Firefox 2.0
Addons kept
AdBlock Plus: wildcards work great for blocking troublesome adsites and iframes.
Permit Cookies: block 3rd Party cookies and/or block all untrusted sites.
Add Bookmark Here 2: an easier way to add a bookmark deep in your hierarchy of bookmarks.
Auto Copy: text selected with mouse is automatically copied (works with Copy Plain Text).
Copy Plain Text: copies selected content as plain-text instead of html.
Colorful Tabs: generate tab colors by domain name.
Paste and Go 2: mapped to a mouse-button this can open a link from your clipboard in a new tab with a single click.
Stop-or-Reload Button: save precious toolbar space by merging the stop & reload buttons.
QuickProxy: turn browser proxy on/off with a single click.
Web Developer: world’s most important Firefox addon.
No-referrer: block the referrer string from being sent to 3rd Party sites.
Bookmark Duplicate Detector: detects and cleans duplicate bookmarks. Also makes backups for bookmarks file.
Kelvin’s Australian English Dictionary: Australian dictionary without all the US-American misspellings.
Greasemonkey: used with Youtube video downloader and Niconico video downloader.
Locationbar2: highlight domain or subdomain, and make sections of the URL clickable.
Menu Editor: edit the context menus, promote Save Image, hide send-to and set-wallpaper.
Configuration Mania: disable SmartBrowsing, Tab button on active tab only, Disable link prefetching.
Extended Statusbar: add some simple page stats to the statusbar.
NoScript: blocks 3rd Party Javascript and Flash.
Addons removed
ErrorZilla Mod: never used the buttons it provided.
Linky: make all urls clickable. (I found Paste&Go worked better for me)
MR Tech Local Install: was useful to install addons from local files, but gained too much uneccessary clutter with recent updates.
Searchbar Autosizer: I eventually removed the searchbar completely, rendering this addon meaningless.
Tab To Window: browser would often crash if I tried to use this.
Restart Firefox: expected to save session and restart browser, but does not restore ALL windows >_<.