Really, nearly everything in the world can fall into this category, so how can one get ideas to create a new concept or improve an existing one? I'm sure there are several methods but I've found most of my success with two.
I'd be lying if I said there was a system to every one of my designs solutions. In some cases the answers do really seem to pop out of thin air.
I think this ability differs with everyone, however I've found ways that, at least for me, increase these occurrences.
My Different ways to increase a "Eureka!" solution to a problem include: doing my best to remove all previous knowledge on the subject, walking away from the problem for a while, watching other people
Unfortunately, the light bulb approach can be random at best. I learned another, more useful, and methodical approach after reading the excellent book Why Not? by Barry Nalebuff & Ian Ayres.
Their concept and subsequently my practice was to apply methodical thought exercises to the problem in need of a solution. Their four steps include:
As you may be able to tell, these methods apply not only to "other" design solutions, but to many other problems to be solved both in and out of the design field.