Did you know you could drag / drop your downloaded XPI extensions into Mozilla Thunderbirds Add-on window?!?

1. Get whatever Extensions you want from http://addons.mozilla.org/thunderbird
2. Download them all to your desktop or wherever you like to keep your downloads.
3. Open Thunderbird.
4. Click -> Tools -> Add-ons (A Little Window will pop.)
5. Drag all your newly downloaded extensions into this little window and you’re in business!!

Sure beats having to install one at a time!