I have used most of the communication tools referenced. I also like Moodle. It is pretty easy to use and you can break groups down into smaller communication groups and let others read their posts. This is good for jigsaws.
I like webinars most because I can do them at home or work while doing other things. It is important to use time wisely and training sessions that are for short durations work well in the webinar forum.
One of the forums I found interesting was OPAL.