there are many great plugins for FF (my friend told me that Opera has all the functionality of them build in, bu i dont believe him )

here are my plugins if sbd is interested
Adblock Plus - (must have) blocking advertisments
Cache Viewer - Browsing and searching in tempfiles
ChatZilla (good to have) - irc protocol client
DOM inspector - Document Object Model inspector
DownThemAll (must have) - potent downloader
IE Tab (must have) - if some pigpage doesnt show itself correctly in FF
Mouse Gestures (must have) - DONT ASK YOU MUST HAVE THIS I AM ADDICTED TO IT NOW
ShowIp (good to have) - IP Adress
SubmitToTab (must have) - Let submit button open new tabwindow
Tab Mix Plus (must have) - many very useful settings if you like tabwindows
UrlParams (good to have) - lets you see and change parameters of webpage
Wizz RSS News Reader - RSS Reader