All kinds of goodness from Mozilla.
A Firefox extension for reading (and organizing) RSS and Atom feeds:
Sage
I’ve got all but two of the blogs I read on it. Couldn’t find a feed for those two.
Under the category “Blogging”, they only have one thing and it’s actually for Live Journaling, but we likes it. Deep Sender
Love the Calendar application, too. It works standalone, with Firefox and with Thunderbird (the email client).
There are at least a dozen other extensions that I installed for Firefox and Thunderbird.