Another one of my rapidly developed mashups - it's an OPML interface for Yahoo! Traffic. Yahoo provides a really decent REST API to their US traffic data. 
It takes a handful of options - the first is "map", which embeds a small Yahoo map in to the outline. This has the advantage of looking pretty, but the disadvantage of reducing the number of results in certain areas (I was testing with towns in MA) if the map isn't available. 
The other option it takes is "zip", which allows you to enter a ZIP code instead of the usual state, city and street mixture. 
If you choose not to enter a ZIP, you should enter at least a state and city or town. 
Certain places are not supported. You shouldn't have any trouble with the big cities - I've tested numerous Californian cities as well as NY, Boston, Seattle, Atlanta and Chicago. I've had problems with tests on Hawaii, New Hampshire, Alabama, Alaska, Utah, South Dakota, Idaho and others. Your mileage may vary. 
Below are some places with different options showing. Feel free to change the URL. (I chose Boston for most of these - because of the Big Dig and the general busy-ness of the place, I know that there'll be traffic problems, at least for a while!
) 
Seattle, WA (Grazr) 
Boston, MA with map (Grazr) 
JFK St, Cambridge, MA (Grazr) 
ZIP 02118 (Boston area) (Grazr) 
ZIP 02118 (Boston area) with map (Grazr) 
I've realised that the street level data isn't particularly useful at the moment - that is easy enough to fix. I also need to know whether people are bothered by the times - I'm not sure what time-zone those times are. I can always do a time-zone lookup (so that it'll give you the right time-zone based on the state you are in), but that's more work. 
Due to the fact that I'm over 3,000 miles away from the US, it's difficult to know whether I've done this right. If you've got any suggestions (remember that I'm only using what's available in the Yahoo API), please feel free to comment or send me an e-mail. 
I'd like to build a similar thing for the UK - although it's probably fairly easy to predict the traffic in the UK (the M25 = a boot trampling on a human face forever, for instance), if anyone does know of any APIs that I could use to build similar little pieces from, either for the UK or for other countries. 
For the states that aren't covered, it may be possible - if you can point me towards a source for traffic reports for that particular state, I might be able to build in exceptions (although I'm not going to spend hours and hours building a complex screen-scraper so you can know whether there's traffic problems in Nowhere, pop. 53., I might be able to build something of a compromise in to the system). 
In short - enjoy. If this helps you avoid wasting your life away in a traffic jam for even half an hour, then it's mission accomplished. I waste time at my computer so you don't have to waste time in your car.

Comments | TrackBack 