Yahoo! groups have, of course, been around for years, and many AAUW communities use them for mailing lists and some use their file storage and general web site features. Indeed, nearly 50 AAUW-related communities are listed in the directory.
Somewhat newer is Google groups. On a quick look today, I found two AAUW related groups — one for International Fellows and another labeled “AAUWbookgroup” that seems to have been an experiment that isn’t going very far. Note that Google also indexes Usenet newsgroups like alt.feminism (full list matching aauw).