mail-archive.com is a free service for archiving any mailing list. Once your list's archive is created, the service will receive and archive all future messages to the list, and offers a web-based interface for anyone to view the list messages (by date or thread) and of course search existing messages.
And yes, someone can even import past messages to stock the archive (http://www.mail-archive.com/faq.html#import). Cool! Better still, it protects the privacy of the list members by hiding or obfuscating their email addresses. They even make it possible to respond to the sender via the archive using a special server mechanism that avoids delivering the address to a spambot. See the info at http://www.mail-archive.com/faq.html#spam and skip to the 2nd paragraph for more. I note they even detect emails in signatures and remove those, replacing it with "[EMAIL PROTECTED]". Very nice. They even have a mechanism to permit a sender to a list to PREVENT their message being archived (by their including the header X-No-Archive: yes). Finally, I'll point out that other CF mailing lists already use it, including the venerable CF-talk list: http://www.mail-archive.com/index.php?autobahn=nolimit&hunt=fusion so a list organizer or list member can check out the interface before deciding whether to use it. If you're interested in doing this for your list, you may want to contact the person who runs it (though, technically, they don't mandate that you be the list owner to set it up). You may at least want to announce your intent on your list to avoid a bunch of members setting up duplicates. Feel free to point them to this very blog entry to learn more.
And on a related topic, if your group's mailing list is hosted on a "groups" site like google or yahoo groups, then you should already have archiving and searching of the list contents there.
If you have a group and don't yet have a list, you should consider those free "groups" services. It's a great way to bring a community together. I've written elsewhere about that. (Update: tipicalcharlie domain is no more, but page recovered using Archive.org.)
PS I do realize that Gmail could help me here, as an individual, but this is about solving the problem for all members of the list.
PPS I'd like to point out that I did previously write an entry on this same topic on another blog but wanted to reprise and update it here for those who may have missed it.