We first heard of these from a post on the Branching Streams website.

Update: The Berkeley based Election Retreat team is hosting another online Letter Writing Retreat Sunday July 24, 10 am to 1 pm, PST. Forty-two people attended their July 10 retreat and wrote over 800 letters. You can register at this link. “Once again we’ll focus our efforts on Nevada, where a Congressional seat, a Senate seat, and a Governorship are all in play. Once you’ve registered, we’ll email you everything you need to participate, including letters, schedules, chants, etc.”

More info and a schedule of future retreats can be found HERE.