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.
update Sunday; June 13, 2010:
Looks like they removed the feature that allowed you see precipitation forecasts. That’s too bad!