1) Adblock Plus: the web page is much cleaner without the ads.2) Add-on Compatibility Reporter
3) All-in-One Sidebar: It appears to be incompatible with the default theme when switching the themes, and the development build has the fix.
4) Chromin Frame: bringing the same look and feel as Google Chrome browser.
5) Chromin Tab Behavior
6) CoolPreviews
7) Coral IE Tab: Originally I was using the IE Tab which is not compatible with the new Firefox 3.6; then I switched to the Coral IE Tab. You need to check the developer's web site for the latest add-on.
8) Dafizilla ViewSourceWith
9) Disablemenu
10) Download StatusBar
11) DownloadHelper: quite handy to use when downloading videos.
12) Fission: Fission combines address bar and progress bar (Safari style). This makes the progress bar more visible and allows for a nice visual effect.
13) FoxTab
14) Google Voice Add-on for Firefox: very neat add-on to recognize the phone number on the page and you can click to dial the number via Google voice.
15) gTranslate
16) Locationbar²
17) Map with Google: Originally I was using the Map This extension, but it was no longer working after I installed gTranslate; then I switched to using Map with Google.
18) New Tab King
19) Organize Status Bar: you'll need it as the number of icons are going in the status bar.
20) PluginChecker: Check at application startup if there are plugins installed without user permission
21) Print/Print Preview
22) QuickDrag
23) Tab History
24) Toolbar Buttons
25) User Agent Switcher
26) WebMail Notifier
27) Xmarks
The theme I use for Firefox is the Strata RELOADED.
Then for Thunderbird, I'm using the following add-ons:1) CompactHeader
2) Display Mail User Agent
3) Forward
4) Hide Menubar
5) Lightning: The Lightning 0.9 is not compatible with Thunderbird 3.0, and I have to use the nightly build.
6) Toolbar Buttons
The theme for Thunderbird is the OWN.