Google Maps finally added real-time traffic info for many U.S. cities to its online site (this feature was previously available only on their mobile version). Living in LA, I have to check traffic maps almost every time I leave the apartment.
Google is no longer the child that can do no wrong. Looking at the LA traffic map, for example, you realize that their traffic overlay obscures the actual highway numbers. That's a severe interface bug. It's not noticeably superior to sigalert, the most commonly referenced LA traffic site. The one thing Google has going for it is that the traffic data is combined with its map site so you can everything in one place. Trafficpredict.com is also useful in LA as it allows you to look up historical time slices.
Some useful mobile implementation of traffic with a GPS device is what we ultimately need here in LA. There may be such a device already, but I haven't come across it. The problem is that traffic data doesn't exist down the the local street level here in LA, and residents here all hop off of the freeways when things get ugly. I don't know how many times I've been trying to drive with an LA Thomas Guide in my lap, trying to find any possible shortcut through the endless stretch of gridlocked metallic coffins we call cars. The LA Thomas guide for LA and Orange County is the size of most world atlases, but it only covers part of LA.