Windows only: POP Peeper is a system-tray application that keeps you updated on new emails in your POP3 and IMAP-based email accounts. For multiple inboxes, it could save a lot of hassle. POP Peeper not only notifies you of the new mail, but allows you to read the messages in HTML, plain text and rich text formats. And the alerts come in many flavors, including a skinnable desktop alert window, sounds, flashing keyboard lights, or an active tray icon. POP Peeper supports plug-ins including screensaver-based notification, voice notification that reads you email headers, and the ability to function as a basic RSS feed reader. While it isn't the most practical tool for reading all your feeds, it could be handy for rare but important alerts, like new software releases. POP Peeper supports unlimited accounts, and can be installed as a portable application. It's freeware, Windows only.