[helsinkiandrew]

The best of these would be something related to a lifestyle business you are interested in as a hobby or would do for fun anyway. So if it doesn't generate a lot of income you are still having fun - importing/selling wine, something to do with antique motorbikes etc.

Your question implies you are looking for tech ideas and your skills are in building software or services. The other side is applying high tech to areas of business that aren't very high tech at the moment - think about all the small or local businesses that still thrive that can barely get a website together and couldn't afford to hire a decent developer or even have the skills to manage a software project - if tech can improve that business you can differentiate yourself.