Upload & Sell: Off
Lots of different things in this thread, and though there's some occasional overlap, they're not really comparable.
- plates (like those developed by Mark Watkins) can be useful on the ground, but they're also often used for mounting cameras with clamps in odd places. They will support essentially anything you can bolt to it. The Kirk Low Pod is a version of this with short feet and a grip for handling/carrying.
- ground tripods, like the RRS TP243, the Berlebach table tripod (despite the name), and the Kirk Low Boy (which is a cut down Manfrotto) are very short, but capable of stabilizing long/heavy rigs, for macro or other low level shooting. The beefiest of these that I've used is a Gitzo baby Series 3, on which you could easily mount a properly balanced 600/4.
- table tripods, which run the gamut from little plastic things like the Ultrapod to the much sturdier but still pocketable stuff like the Leica table tripod and the Kirk and Manfrotto variants. The tiniest of these are wobbly and would likely never be used except as a supplementary support or for a quick platform for a point and shoot; the sturdiest are quite strong and stiff (Kirk and Leica, in particular), though their short legs and subsequently narrow platform makes them less sturdy with a big rig than a ground tripod. Not great in the dirt. I'd have no qualms about using one to help me stabilize a supertele on a car hood or other flat surface, though.
Personally, I use a Berlebach for ground level macro, a Leica table tripod for travel with a DSLR or my NEX, and I have an Ultrapod in the glove box for my wife's S90.