1) Best add block addon for firefox.....it blocks almost all adds n increase browsing speed......
  https://addons.mozilla.org/en-US/firefo ... e1a2a59166

2) This addon gives u tab view like that of chrome......u can costomize it according to ur requirement
    https://addons.mozilla.org/en-US/firefo ... e1a2a59166

3)Skipscreen is an addon that skips screen when on some sites like rapidshare, megaupload,etc u hav to wait for 30-60 sec......it directly fetches download without wait
  https://addons.mozilla.org/en-US/firefo ... e1a2a59166

4)Smoothscroll is an addon that changes ur webpage scrolling xperience
  https://addons.mozilla.org/en-US/firefo ... e1a2a59166

5) If u lyk to listen to music while browsing then using this addon u can control ur music player thru firefox.....u get a toolbar at bottom to control music
  https://addons.mozilla.org/en-US/firefo ... e1a2a59166