GarminF is a very popular discussion group on Yahoo! that focuses primarily on Garmin Forerunner and Edge models.
GarminF has quite a few active members and generally sees a few hundred messages posted per month. Messages are on topic and are well moderated. It's a great place to share information and ideas with other people who use Forerunner.
If you decide to visit, please mention AthleticGPS.com in messages where we can be a resource.
Here's a link: GarminF on Yahoo!