I got a link to the Forecast Advisor from the Freakonomics blog. Wow! You have the forecast for today and the next few, but much more data as well. Clicking on a day allows you to see previous days' forecasts for that day (indicating stability of forecast). It also lets you know how accurate various sites have been for the last month and year. And that's not all. There's all kinds of cool discussion on their FAQ.
Data! Geekery! Wow!