The cynic in me always suspects these questions are fishing attempts to see what ideas can be cloned to steal some of the revenue.
"Wanted: a feasible business idea not quite lucrative enough for the proprietor to be able to afford to take legal action."
Also it could be the other way around, you need a solution for a problem you have. Say that you built something profitable and wait 'til someone "copies" your idea.
Copying an idea and writing code will get folks maybe 10% of what goes into building a sustainable business, so I'm not too worried myself.