I have the Bags-Connection Engage Tank Bag on my bike (twistedthrottle.com). It uses the SW-Motech tank ring allowing the bag to clip on and off the tank without the use of straps or magnets. The gas cap ring elevates the tank bag slightly above the tank allowing for minimal contact with the gas tank.
http://www.twistedthrottle.com/trade/productlist/171/
