All-in-one gestures (disable all unused guestures) Right click and make a squiggle. I use it to close tabs.
greasemonkey You need it for the scripts in the scripts part of this article.
rikaichan (with names dictionary, press return to switch) The best tool on the net for reading any Japanese webpage. Or even mine sometimes.
submit to tab
Scribefire Useful when I post for wordpress blogs like Japanprobe
foxmarks Syncs my
GButts All your google pages next to the URL bar or wherever.
Resurrect Pages Useful for dugg-to death pages.
tab history New tabs have the history of the page that spawned them.
tab mix plus Essential.
Context search Lets one search highlighted text with any search engine they have installed into the search bar.
google cache continue
google MP3 Puts a little play button next to MP3 links you can listen with.
Textarea backup Essential for not losing stuff you said or want to say again.