SignatureProfiler is a plugin for Apple's Mail application that adds missing features from the way that signatures are handled and managed with your outgoing mail messages, especially if you have multiple mail accounts (and who doesn't these days). It was originally written to make up for the complete lack of signature management in versions 1.x of the program, but even 2.x is still missing some capabilities if you use several different accounts and want to share signatures between accounts.
Mia for Gmail (was Notifier Pro for Gmail) is a desktop Gmail client which sits politely in your menu bar.
