Some train related links spiraling out from Seattle.
History of the Highland Park & Lake Burien Railroad. This was a trolley line that went from Seattle, south to what is now Burien, in the 1910s to 30s.
Sound Transit - commuter rail, light rail, and express freeway buses in the Seattle area.
Amtrak's page on the Cascade line - Portland to Vancouver
Metro Employee Historic Vehicle Association - maintains historic trolley buses, and gives tours on them periodically.
Spirit of Washington Dinner Train - fine dining on a train that skirts the East side of Lake Washington, near Seattle.
Iron Goat Trail - an interpretive hike in the Cascades that passes several tunnels and snow sheds along an old rail line.
Iron Horse Trail - another rails to trails program. This one is much longer, and includes the Snoqualmie Tunnel, a frightening 2.5 mile tunnel. A nice bike ride.
WSDoT's King Street Station renovation page - photographs of the real thing
Snoqualmie Railroad (Northwest Rail Museum). Easily accessible from Seattle, they have a nice museum, a fun 15 minute train ride (hour round trip including stop), and a ton of rolling stock and engines just sitting around.
Mt Rainier Scenic Railroad - fun hour and a half round trip steam ride in Elbe (about an hour SE of Tacoma).
WA Steam Railfan - lots of info on steam trains in Washington State.
NYC Subway - an excellent site. Especially enjoyable is the section on abandoned stations and lines.
Osaka, Japan's Modern Transportation Museum - excellent. car by car photos.