I've put together a website where you can view interactive graphs of the weather - pan and zoom through the full history of a weather station and get multiple forecasts for the current location, all overlaid on records and averages for the weather station: http://weatherspark.com
Pan the graph by clicking and dragging. Zoom with the mouse wheel, and there are zoom shortcuts up left of the graph. Pick the data series to show in the "More Graphs" section. Use the map to quickly browse through the world's weather, station-by-station. Search for any location on earth.
It's still in beta, so please pardon any rough edges in the application or glitches in the data - weather stations sometimes report bogus values, and we're working to sort those out. We currently have > 4,000 stations, but are working to add more (it's primarily METAR right now, want to add Mesonet/PWS as well). The current conditions are updated once or twice per hour, we're working to make them effectively instantaneous.
Would love to hear your thoughts on it. Which data series are your favorites? Which ones are missing that we should add?