Postbox - If you're not using your email's web interface, use this. It's basically Thunderbird, the open-source email client we'd previously included in our Lifehacker pack, but remixed with stronger, almost Gmail-like powers. It finds and indexes all the attachments in your email account, groups together conversations with similar subject chains with the "Gather" command (like Gmail's conversations), offers tabbed inbox and message views, and lets you organize emails under your own chosen "Topics." It's also got built-in easy setup steps for Gmail and other webmail systems—in other words, everything we're waiting to see Thunderbird implement. [Download]