Adorama offers the Spinlight 360 Extreme Modular Shoe Mount Flash System for $99 with free shipping. This lighting system is compatible with the Nikon SB-600, Nikon SB-700, Nikon SB-800, Nikon SB-900, Nikon SB-910, Canon 580EX II, Canon 580EX, Canon Speedlite 600EX-RT, Canon 480EX II, and Sony HVL-F58AM flashes, as well as other flashes of similar size.
We have ours and have been playing with it and should have our full review available soon.