Updated June 6/2017
Tripod Accessories, Bowl Adapters, Quick Release Plates
Vanguard Multi-Mount 6 Tripod Utility Bar - $99 - more
Multi-Mount 6 enables you to mount two cameras or camera accessories such as a flash unit to a single tripod. It quickly and easily attaches to the tripod. Multi-mount attaches easily and quickly to your tripod with a 1/4"-20 screw and uses the same size to fasten your camera, flash, spotting scope, a second camera, etc. to the two sliding bar heads. At each end of the Multi-mount is a 3/8"-16 screw for attaching a ball head, pan head, etc. Please make sure your tripod is stable to prevent tipping. Dimensions (Diam. x L) 1.13 x 24" (28 x 450mm) Weight 2.36 lb (1.07 kg)
Promaster Dual Axis Bubble Level - $10 - in stock
Just slide the bubble level into your cameras accessory shoe and adjust your tripod head until you achieve level. The dual axis design makes it easy to achieve a level horizon when shooting either horizontally or vertically.
Find thread adapters here
Find tripod dollies here