You're clearly a good writer so play to your strengths.
- Have you considered translation services? I know you're in Germany but clearly have an excellent grasp of English
- How about a resume-writing service?
- There are a number of companies that offer "drop-ship" services. There's a page here which lists some of them
- Environmental issues are huge right now. Not sure how you'd enter the market in the context of a home-based business, but I imagine there are opportunities there
- Possibly some sort of services broker. A buddy of mine has just started working with the "green building" trend (also ties in with environmental) and he acts as a broker between homebuilders and suppliers of "green" materials.