We might not be the biggest, but we personally guarantee that our listings are the most accurate. Click for info on CD-Rom status and availability. Brian Edmonds has written a FAQ on mailing list service providers , as well as one for mailing list etiquette . Both are highly recommended. New mailing list index at Meta-List .
Tile is another source for mailing lists.
The International Federation of Library Associations site is an impressively good overall resource. Mailbase is a mailing list service based in the United Kingdom. Prodigy has its own listserver, hosting numerous lists for just about any interest. A plethora of lists awaits you on Plaidworks . All you history buffs might want to peek at Internet Mailing Lists in History , as it's a useful and informative site.