Flashblock and Adblock. Essential. Absolutely essential, and the
main reason I keep using FireFox instead of Camino or Safari or
Omniweb.

Omni's got the session-saving and, actually, lets you keep set of
sessions. But no flashblock. My kingdom for a 2x4 with which to
beat folks who build flash-only websites and/or put flash with *sound*
on sites.

I'm getting SessionSaver now.

Oh, and Ask.com searches have the little previews built-in. Mouse over
the little binoculars.