For Web Developers, one of the most important plugins for FireFox is the FireBug. A enhanced in-Browser Javascript-Debugger (and more), that allows to quickly find bugs or monitoring odd behaviour. Drosera is a usefull application that offers similar features for WebKit-based browsers, like Safari.
So next time you have an odd bug in your Javascript-Code, instead of chasing it down via tiring alert() or console.log() sessions, you could just as well try Drosera, which offers an enhanced interface, and many a option similar to FireBug.
