Since Sparrow fell off the radar, I've adopted Postbox as my email client of choice. Though I've given Apple's native Mail.app a try for short periods of time in the past, I simply don't prefer it. That said, this post from App Storm may have convinced me to give it another try. It's packed full of useful tips, suggested tweaks, and other information to help you get the most out of Mail.app and your email workflow.
If you're already a Mail.app user, then you should definitely give it a look.
If you use a different Mac or web email application, then perhaps this post will convince you to give it a(nother) try.
(via 52 Tiger)