There are lists for topics ranging from general discussion to Vintage Macs to iMacs. Another source of mailing lists is Topica . Topica is a list server and they have an evergrowing number of lists on most topics. A couple of the Mac lists I subscribe to have moved there. They have 20 or so Mac specific lists and the site is searchable.
T here are also a number of local commercial companies which specialize in Macs.
T here are also many websites which contain articles and tutorials which are of great value. Term definitions, file formats, emoticons and much more. The complete guide of every Macintosh, Mac Compatible, and upgrade card in the world, with detailed technical, configuration, and pricing information. There are a number of help articles and volunteers you can e-mail. What are all those extensions for.