for those of you that drive in the US and also have iPhone this may be of interest.
The company I work for just released a free app for iphone that shows you realtime and predictive traffic nationwide. It's very neat. I think so anyway!
I didn't build the app as I'm a GUI idiot , but my code does all the calculations of speeds on the road that support it
anyway there are details here: http://inrixtraffic.com