Roads and Highways

Ratetheroads.com - A guide for conditions of facilities as rated by website visitors.
http://www.ratetheroads.com/

Worldwide Transportation Library - Covers North America (primarily the Western U.S.), Asia and western Europe.
http://wwtl.info

CatSynth.com - Highways - Contains commentary and information about various routes.
http://www.ptank.com/blog/category/highways/

Me and the Roads - Java game involving road-building.
http://www.kurumi.com/roads/matr/

Trans Global Highway - Proposal by a private citizen to construct a global railroad and vehicle highway around the world including a tunnel under the Bering Strait from the United States to Russia, from Sakhalin in Russia to Hokkaido in Japan, and from Spain to Africa. Includes maps.
http://www.didik.com/highway/

CBRD - International - Page from Chris's British Road Directory illustrating the differences between roads in Great Britain and those in Andorra, Australia, Cuba, France, Iceland, Italy, Ireland, Mexico, Pakistan, Spain, and the United States.
http://www.cbrd.co.uk/reference/international/

Mike's Railroad Crossing Website - Covers the United States, Canada, the United Kingdom, and Australia. Also includes picture-taking guide, links, and FAQ.
http://www.rxrsignals.net

Mark Furqueron's Highway Page - Includes views mostly from the American West, predominantly California, as well as Asia and Europe. Includes pages on removed vintage signage.
http://members.cox.net/mkpl/road.html

Jonathan's Photographs - Culled from various trips around the world.
http://winklers-roads.fotopic.net/

SABRE Photo Gallery - Contains examples from multiple continents, notably of Great Britain and Ireland.
http://www.sabre-roads.org.uk/gallery/