You can look up many services on the directory at NRW AngloFile. This directory describes in English what the business does, but it is one where business have chosen to be listed. This directory also covers all of NRW so some businesses are as far away as Essen.
MyHammer.de is a good place to go to look for reviews of local business, but it is all in German. You can type in the name of the service and your zip code and find out how the business is reviewed by people who have used them. You can also submit a proposal for contractors to bid on.
The sites listed here are ones that have been recommended by expats living in Bonn.
