For a consolidated view of your POP accounts, try MailBell Email Notification 2.03 ($15 shareware) or PopTray 2.1 (free). Both let you set a variety of audio and visual notifications for new mail, so you can classify urgent and important messages by subject and sender or automatically delete spam. And both tools provide simple displays of your in-box for notification management and access to all your new mail across your POP accounts.