Hi james_a and welcome.
Thanks for the PM invitation to this thread.
My District uses a Yahoo group for district business and discussions. Subscribers are generally limited to current and former DSC members, though others could join if they wanted to. The list is used to disseminate event information, but principally so that GSRs can carry the news to their meetings. The list is not used for event planning nor sharing. Other than email, I am not aware of any online resources used by those involved in planning.
I think my District needs a better way to communicate events. My district Yahoo group is not something your typical member would be interested in joining (too much uninteresting traffic that would feel like junk mail). While event information is often posted on the district website, most members don't visit often enough to keep informed (even if the info were to be up-to-date).
I recently floated the idea of using Twitter, and I expect we'll talk about that at the next DSC. One way or another, I believe we need a way to "push" event announcements to members. My guess is that a dedicated Yahoo (or Google) group is the answer since "everybody" has email and only some use Twitter (Facebook is popular in some circles but it also requires membership, is a privacy risk and is less anonymous than Twitter, IMO). If limited to event information, maybe vast numbers of members would subscribe.
I like to post event information here on the forum, but I do it to expose newcomers to some of the fun in MA and to give members ideas for things that they may want to try in their own districts. I do not think that it's the most effective way to get the word out: it's like the District website in that regard. It's not "push" - people have to go looking for the information.
I did set up a Google group for my Sunday meeting, but the response was underwhelming to say the least. YMMV.
Please share any ideas that work for you and let me know if I missed anything....