Here's the link for the yahoo group: http://groups.yahoo.com/group/seattlekayaker
The Washington Kayak Club is the main club and very active, www.washingtonkayakclub.org
There are pool sessions every Wednesday night in north Seattle and on weekends in the winter at a bunch of locations.
This is an ugly year out there with the lack of snowpack, but the Sky runs year-round and there's always something going somewhere. Take your kayak to Westport for some ocean surfing or head up to Skook.
There aren't any kayak parks out there, and damn few park and play spots, but no shortage of great rivers and creeks. And, most years, no shortage of water.
Tell everyone hi for me.