Some Useful firefox plugins

Tab Mix Plus - Plugins that enhance Firefox tabbing function. If you ever accidentally close a tab that you didn't want to close, tab mix plus can give you option to lock a tab, so you wont accidentally close it. it also allow you to lock a page so it wont go to another tab while you clicking on a link making cross referencing materials easier

Adblock Plus - very useful plugins to block popup and annoying advertisement. blocking advertisement can save your bandwidth and increase page loading time.

Noscript - work with similar policy with adblock plus albeit with regard to JavaScript. Its wont allow javascript in webpage to run unless you white list them. this plugins is very useful especially when there a lots of site using JavaScript for malicious purpose .

Flashgot - best download manager integration for Firefox I've found so far. some download manager, flashget for example, didn't support Firefox web browse so this plugins come very handy.

Download Manager Tweak - for those who like to stick with default Firefox download manager, DMT is a good improvement for firefox downloaded. it further enhance button, re download deleted file and more download detail