Try the new Trip Planner, which can help you create custom transit plans. It currently provides information for Metro, ST Express routes operated by Metro, & Sounder Commuter Rail service.

Ride the bus in King County - Metro
Is my bus late?
Where is my bus?
Ride the bus in the region - ST Express
Ride the commuter train! - ST Sounder
Sound Transit - our Regional Transit Agency
Travel to another city on the Amtrak Cascades or the Coast Starlight or the Empire Builder
Check for sale prices with Amtrak's rail sale online discounts
Free, frequent light rail is coming to Tacoma AND until then.
Ride the Elliott Bay Water Taxi. Also adds a free shuttle bus around Alki.
An extremely successful light rail system nearby - Portland's MAX
Another nearby successful rail system - Vancouver's Skytrain
And so on, ...
The ETC is working to build a monorail system in Seattle (within city limits).
Friends of the Monorail - A monorail advocacy group (obviously).
Freeway|monorail is a proposal for a regional monorail system.
More links
More soon ...

Revised when I can, most recently noted Feb 7, 2002
Carfree Seattle
Comments & suggestions