I just like convenient plugins. Many are a bit ridiculous. However, among convenient ones are:
Gmail Checker if you have Gmail.
DownThemAll! is nice if you sometimes find yourself downloading several things at a time and want a more informative download manager.
AdBlock Plus is awesome for obvious reasons (do other browsers have such effective adblocking tools? I'd like to know)
And if you want to put a link in your signiture or something else that gives limited characters, try Tiny URL Creator.
Here is a list of plugins NOT to get.
Nowhere near complete list.
Babelfish Instant Translator: Always seems to pop things up when reading text. If you disable it without uninstalling it, it'll still function by feeding ads through text. If you uninstall it, no more problem.
