http://chicagotraffictracker.com/

Tribune Hilkevitch column about it here

CDOT is quietly experimenting with an amazing web site that shows real time street speeds, congested zones, traffic counts, red light cameras, signalized intersections and Holy Cripes: intersection-specific pedestrian counts!  I understand that much of the data for the street flow is generated by GPS signals off of all the CTA buses moving at the time, but I can't imagine how they're getting pedestrian data in that level of detail.  If it's accurate, it will provide great information for urban and traffic planning in the future.  It would be interesting to watch the red congestion zone move around the city on Critical Mass Fridays.  And it would be really interesting if they could somehow parse out bike traffic numbers and speeds from motorized traffic on a real time basis, particularly on the lakefront path or popular arterials.

From John Hilkevitch's article: A broader range of data may encourage people with flexible schedules to travel at different times or to take a nearby CTA or Metra train when arterial traffic is crawling, officials said.
"It may recommend that you take the Blue Line instead of drive," (Gabe) Klein said. "The goal is to help people make informed decisions and reduce congestion on city streets."