Ride with others in a personal vehicle.
Traditional: Search for and set up an ongoing carpool using RideshareOnline.com
Real Time: Set up a carpool within specified commute hours with Scoop or iCarpool
Join and use a vehicle when you need it (and don't pay to park it when you don't need it).
Ride with others in a King County Metro van; keep the van at the driver's home (Vanpool), or take it to and from a transit hub to cover the first and last mile of your commute (Vanshare).
Request a car and driver to pick you up and take you to your destination.