Firefox extensions that are a must

MUST have extensions:
noscript denies Java, and JavaScripts from running, unless whitelisted.
adblock – Just as it sounds, blocks ads.
a large list for adblocking – a community list for adblock
Disable Targets For Downloads – Prevents sites spawning blank windows when clicking binary downloads.
Tabbrowser Preferences
gmail notifier – little notice icon when new mail arrives to your gmail account.