Zogby Polls has this interactive map of the United States, showing presidential polls in 34 states. Each result shows results for Obama, McCain, Barr and Nader, and an “other” category, plus an “undecided” category. One clicks on any particular state (or, for the very small states, the name of that state), to get results for that state.
There are no results (as of July 9) for Alaska, Delaware, D.C., Hawaii, Idaho, Kansas, Maine, Mississippi, Montana, Nebraska, North Dakota, Rhode Island, South Dakota, Utah, Vermont, West Virginia, or Wyoming.
According to this poll, Barr’s best state is New Hampshire with 10%, and Nader’s best state is Massachusetts with 3%. Thanks to Kevin Takenaga for the link.