This is still work in progress. It's already useful, but not intended for productive use. Features may work or not and are very likely to change without prior notice. See also Slideshare presentation in german
Search for WFS layers in this catalog. Contribute WFS you know by submiting URLs. Please take note of usage constraints and fees before using WFS to download geodata.
Use export for QGIS to generate a XML file with all services known to the catalog with the number of layers in brackets QGIS XML WFS connections
Use WFS Downloader
or your GIS to get geodata you want. URLs used in the crowd mode of WFS downloader are automatically submitted to this catalog.
WFS-Downloader needs GDAL to work, not just the libs, but also the tools! Get the binary package (Generic installer for the GDAL core components) from here: GISInternals Support Site