Search the web for "Ravenna Kibbutz" for a (mostly but not all Jewish) commune in Seattle. As others have mentioned cohousing and intentional communities would also fit the bill.
Excellent article. I love taking the train from Seattle to Portland or Vancouver, BC. The coast scenery is amazing and you avoid I-5 traffic. The Amtrak Cascades is rarely delayed, but the Coast Starlight coming up from California is almost always very late.