One of the most common and universally useful Umbrella's is the Black-backed Silver Umbrella. Silver umbrella's have a foil type coating, so they are very efficient at bouncing light. They also spread light widely, due to the angled fascias of the umbrella.
They can be very useful for flooding entire areas with light, but care should be take where shadows are cast, as the angled fascias on this particular umbrella are prone to causing double-halo shadows.
The catchlights are quite attractive, with a "sparkle" type feel to them.