Cool Novel Precipitation Forecast
For all the European and particularly German crowd out there: Wetteronline.de has a novel feature out, at least novel to me. You can have cloud-cover and precipitation forecast, on a map covering most of Europe, and you can choose at what time, up to 20 hours into the future. The trial version is free and excludes current conditions.

Screenshot of the cloud and precipitation forecast at wetteronline.de
update Sunday; June 13, 2010:
Looks like they removed the feature that allowed you see precipitation forecasts. That’s too bad!