Perfect for adding equipment on top of your DSLR or for setting up flashes on a stand / tripod. I haven't uses it for flashes so I can't say much about the umbrella hole and so forth, but everything looks good with this gadget.
Full name: 1/4" Screw Tripod to 3-Hot Shoe Adapter Holder - Black
Webshop: DX.com (Deal Extreme)
Price: $9.90 (Free shipping)
Lightweight, solid construction, actually feels like aluminum. Perfect in combination with a hotshoe screw to mount both a LED and a mic on top of a DSLR. Good and easily operated screws. Comes with a 3/8" - 1/4" converter / adapter so it can be mounted on both sizes.
Haven't found any so far. Technically it's not a hot shoe, but a cold shoe since it doesn't have any electrical connectors.
Buy it here