Abe's of Maine offers the Vanguard Grip Ball Panoramic Tripod Head
, model no. GH-200, for $169. Coupon code "DEALNEWS12" cuts it to $157. With free shipping, it's the lowest total price we could find by $13. It features a universal quick shoe and supports large zoom lenses to purportedly provide better panoramic photography.
Update: A reader notes that B&H Photo-Video offers it for $149 with free shipping.