It would be nice to have a mailing list just for the conferences. Ideally, every conference gets its own mailing list.
In this mailing list you could;
* Promote your talk.
* Read the reactions of the public.
* Ask for a squash buddy in the hotel you are staying
* Provide last minute conference information
* Share the password of the subnet for the presenters
* Share links to presentations
* etc ..
It would also make a nice archive for every conference.