These are must have add on's. how can you live without them??
Blocks annoying video ads on YouTube, Facebook ads, banners and much more.
Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable).
Leading dictionary lookup add-on. Fast, light, open source tool that define words for you without need to open new tabs or windows. Wiktionary&Wikipedia.
Ctrl or Shift or Alt + RightMouseButton click. Now with thesaurus.
70+ languages supported!