Necessity is the mother of invention. Two websites that focus heavily on the necessity part are halfbakery and ShouldExist (as in a space should exist between two words). Both are online idea banks with some fairly good posts and intelligent comments. At halfbakery, posters put forward their ideas and visitors then vote for or against it (with croissants, no less), often alerting the inventor of similar ideas that have already been “baked” by others. ShouldExist focuses more on problems that cry out for solutions, like the top post which wonders why a GPS device can track to within metres of area codes and radio stations but can’t adjust for timezone changes.