NY (upstate/central) - drivers around here are not very good at merging. Lots of times they'll make it very difficult to merge, or to let someone merge. Slamming on the brakes at random times seems to be a local favorite. The Syracuse University area also seems to have it's fair share of people from areas that don't get much snow, driving SUV's, with no idea how to drive on snow/ice. (hint: 4 wheel drive isn't going to do you any good if you're on a sheet of ice)
MA (boston) - Only drove here for 4 days, but it was enough for me to learn a few things. Stopping or slowing down for yellow lights is not done. Stopping for a red light is considered optional, as is the use of turn signals. However, you do NOT go more than 5 miles over the limit on the Pike, there are troopers EVERYWHERE.
OH (anywhere) - driving slow in the fast lane is standard practice. Driving slow in the non-fast lane is also standard practice. Turn signals are used sometimes, but are often inaccurate (either turning on wrong direction, or turning it on then not turning). Drivers tend to get irritated at others who want to pass.
MI (Ann Arbor/Detroit Area) - being an Ann Arbor native, I consider myself part of this group. We drive fast and pass on the right. Traffic signals are generally obeyed, and turn signals are used more frequently than not. However, it seems to take far too long to exit a venue after an event. Doesn't matter which venue, or which event, anything with a crowd over 2,000 will cause traffic problems exiting the parking lots.