http://thestandardsmanual.com/ The design manual created for the NYC subway by Vignelli.
http://transitmaps.tumblr.com/ Real and fake public transportation maps from all around the world.
http://sumo.sourceforge.net/ SUMO simulates traffic patterns over large road networks. It has a GUI and can pull in maps from OpenStreetMap.
http://www.looksgood.de/log/2011/10/mapmap-vauxhall-mashup-mental-maps-and-openstreetmap/ This software allows users to draw a mental map of an area and squish the real map to their drawing. There's no demo available but there is code on GitHub.
http://www.nytimes.com/2011/07/25/nyregion/deep-below-park-avenue-a-200-ton-drill-at-rest.html A massive drill bit used to create NYC subway tunnels will be left underground and encased in concrete.
http://www.youtube.com/watch?v=PN_oDdGmKyA The world's longest model railway!
http://en.wikipedia.org/wiki/Braess%27s_paradox It turns out that adding road capacity can sometimes cause worse travel times.
http://www.nytimes.com/2011/01/12/nyregion/12taxi.html?_r=1&em Turns out 5:00 is a bad time to find taxis in New York for some interesting reasons.
http://traintimes.org.uk/map/tube/ Watch the location of London Underground trains in real time!
http://thelaunchbox.blogspot.com/2011/01/view-down-below-january-23-2011.html See the construction of the Second Avenue Subway.
http://www.infrastructurist.com/ Infrastructurist is an excellent blog covering news stories about America's transportation systems.
http://www.capitalnewyork.com/article/culture/2010/12/915879/new-york-subway-map-wars-continued An article about a panel discussion over New York City's subway maps.
http://en.wikipedia.org/wiki/Gate_Tower_Building The Gate Tower Building has a highway ramp built through it. Wikipedia also has a list of structures built on top of highways.
http://discoveringurbanism.blogspot.com/2009/12/dreaming-about-magic-highways.html An old cartoon predicting the highways of the future.
http://mutcd.fhwa.dot.gov/kno_2009.htm The MUTCD is the national standard for highway signs.
Gil's LotD (Link of the Day) publishes a link to a web page every day. The linked pages are chosen for their interesting, informative or entertaining content. You can read Gil's LotD on the web or in a daily email.