The following sites are general newsgroup and mailing list sources.
Microsoft.public.powerpoint
This is the official Microsoft PowerPoint newsgroup, and it's where many of the PowerPoint MVPs hang out on a daily basis to help answer tough questions. Therefore, it's a great starting point for troubleshooting and general information. Access this through a news reader program or through Google Groups (http://groups.google.com). You can also access the newsgroup through a Web interface at http://communities2.microsoft.com/communities/newsgroups/en-us/default.aspx.
www.freelists.org/cgi-bin/webpage?webpage-id=mso
A free public forum for people who want to talk "questions and answers" about Microsoft Office products.
http://groups.yahoo.com/group/powerpoint
A mailing list group for people interested in discussing PowerPoint. Many of the same people who participate in the previous two groups are also subscribers to this list. This is the same as eGroups, which merged with Yahoo Groups.