Guide Review - Mail Forward for Mac OS X
This nifty utility collects mail from multiple accounts and forwards it to any email address (or more than one), where you can read it comfortably. Mail Forward can do its forwarding automatically according to a schedule, or you use AppleScripts to control its functionality. All the while, Mail Forward operates in the background, configured via a System Preferences pane.
Of course, Mail Forward can also pick up messages from regular POP or IMAP accounts. Unfortunately, you cannot select IMAP folders other than the Inbox, though.
All this makes Mail Forward extremely useful, but it could probably be even more useful if it acted as a simple POP (or maybe even IMAP) server instead of forwarding.
(Updated September 2011)