Good basic explanation - http://www.matsuo-bridge.co.jp/english/bridges/basics/truss.shtm

Truss bridge designs - http://bellnetweb.brc.tamus.edu/res_grid/trussb/designs.htm

Long truss bridges - http://www.matsuo-bridge.co.jp/english/jigyo/bridge/e-kyo_3.html

Lenticular truss bridge in Pittsburgh - http://www.fhwa.dot.gov/eihd/smithfld.htm

Minnesota's bridges by type with pictures - http://www.mnhs.org/places/nationalregister/bridges/bridtype.html

Photo of bridge in Maryland - http://www.eastplaza.com/maryland/baltimore/nw/nw320.htm

Truss bridges in China - http://bridge.tongji.edu.cn/bridges/beam/beam.htm

Truss bridges of Northern Carolina - http://community-2.webtv.net/DAROSAMARCIELII/TrussBridgesof/