Gmail-Users - join
Talk about Gmail, good or bad.
Medium activity, 17936 members, moderated

GMusers- GMail Beta & Beyond - join
A core group of GMail users who expect to be using GMail through beta and beyond. The list is moderated. There are multiple moderators in order to preserve diversity of opinion and a smooth flow of posts. GMusers is open and globally inclusive. You do not need a GMail account to join.
Low activity, 3195 members, moderated

Google-Firefox-Extensions - join
This is a discussion forum where you can exchange information and discuss Google-developed extensions for the Mozilla Firefox browser.
Low activity, 5027 members