We've reported on several types of waist-type camera grips here on Crave. One of them is the, which attaches to the tripod mount of the shooter and slides into a base that's fixed to your belt. The b-grip does the same thing, except it can hold up to 17.5 pounds of weight and doesn't swing around when you move.
The unique feature of the b-grip is that it can be attached to virtually any strap. So if your backpack has a chest strap, you can fix the holster to that, too. Also, it allows users to affix the shooter either lens down or facing outward. A supplied rain cover protects the camera if you're using it in wet environments.
However, we wonder how will it feel to have a pro dSLR such as the Canon EOS 1D Mark IV tugging at your hips. Also to be noted is that the b-grip is made of plastic, so it's not as tough as the Spider Holster, which is constructed from metal.
If you're still interested, check out the b-grip from OmegaBrandess, which is selling it online for $79.95.