Im trying to think of a way to visually make grouping 'a set of businesses' more interesting. The only examples I can think of are the google circles, the iphone app group functionality (having a snap of the icon but in this case the providers picture). Other than that, its mostly cliche folders.
Any ideas would be greatly appreciated.
I might try and group them based on the context of the situation. I don't know what kind of businesses you're working with but if, for example, you were trying to logically group plumbers and electricians I might group the plumbers' icons with sections of copper pipe and the electricians with wiring or circuit diagrams. This would work for grouping things into any sort of predefined categories. If users can define their own groups, perhaps they could drag and drop icons into groups that connect themselves with a customizable web of varying color and texture (e.g. neon bendy-glowstick, red yarn, or wood segments).
