A complete index of USGS topographical maps (2011 version) for Washington state. They are in 7.5-minute by 7.5- minute geographic format.
These maps are free to download at the USGS online store, they just don't have a download all button.
info: http://nationalmap.gov/ustopo/
store: http://geonames.usgs.gov/pls/topomaps/f?p=262:18:2260051864249616::NO:RP,18::