FoxyProxy is an advanced proxy management tool that completely replaces Firefox's proxy configuration. It offers more features than SwitchProxy, ProxyButton, QuickProxy, xyzproxy, ProxyTex, TorButton, etc.

Key features include animated statusbar/toolbar icons show you when a proxy is in use, define which proxy to use (or none!) for arbitrary URLs using wildcards, regular expression, whitelists and blacklists.

You can also define multiple proxies and order their use with priorities so there's no more wondering whether a URL is loaded through a proxy or not.