A cool Google Spreadsheet has been circulating around that details a large variety of live twitter chats that are occurring on a regular basis.
Each chat uses a unique hashtag to facilitate scheduled live conversations via twitter. Everyone is free to add to this list, and when I last looked there were 556 simultaneousness viewing it.
Take a look through to see if there are any topics that are of particular interest to you.
Kudos to @swanwick for getting this list started