GMail addons

Increasingly I'm online away from offline apps like my Thunderbird and Firefox, which means I don't get my settings and addons that I've setup in Thunderbird as I use GMail online. What Google really need to launch is an addon mechanism for their GMail and other services, in the same way that Facebook support users adding apps to their profile etc. So wherever I login.. I get my setup!

Thunderbird needs Conversation mode

Coming from GMail back to Thunderbird on my laptop I'm experiencing all the issues that GMail neatly fixed.

Displaying email threads in "Conversation mode", hiding top posts (see email 101). Reply to an email you've sent and the reply only goes to yourself.. not the same people in the first email.! -- it's a long list. Not even sure if Thunderbird is maintained any more, it hasn't had any new features since it was Mozilla messenger back in 2000 as far as I can see. Addons are good though ;)