i would call it subwoofer isolation platform, but that is too upscale for my tastes. a few months ago i built a platform for my sub to compensate for our uneven floor so that i could level it out. i suppose one could say that it decouples the sub from the floor, etc., but my main reason for building was to keep it from being unlevel. i still dont know why velodyne would put a sub in the class of mine out with little plastic feet (i think they have changed this now though). i was going to mount adjustable screwed in feet into the sub, but for resale purposes (you never know) i decided not to. it cost me about $5 to make the platform which is the cost of the felt and glue. since i was using wood from an old bookshelf that was junk (wood was good though), i had to attach 4 pieces (2 parallel on top layer and 2 on the bottom layer perpendicular to the top). so i had a four board square. i then cut five circular holes through the bottom layer of boards (four corners and middle) so i could mount my recycled speaker stand feet. the adjustable feet had a aluminum head that a scred threaded into and spikes on the cones on the bottom, so i had to be able to rest the heads in the holes on the wood. i would take out the middle spike if i did it again, because it is too hard to adjust... after a few weeks of use and one move with all the spikes falling out i gorilla glued them to the stand so that now they are way easier to move and subsequently adjust. oh and i felted the stand with black felt (because its breathable next to my laquer finish on the sub, cheap, easy to work with, and decent looking). my sub weighs a ton, so i needed a stury platform. i just stapled the felt to the bottom of the platform out of sight, simple but effective. anyway i thought i would post something in this forum to validate its existence and possibly draw some other posts to it.

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i saw some stuff there, but the one thing i saw that you might be talking about i couldnt really see what it had/was. i didnt spend hardly (5-10$) anything on my platform, and i am pretty satisfied with it. well as satisfied as i can be from a stand, i.e. it serves its purpose.
i dont really buy into the idea of spending so much money or accessories for your system (like that site has a bunch of), unless you have the $ and a theatre room (designed for theatre during construction). a lot of times that stuff is a waste, excessive room treatments, like rubber feet, bridges for your cables, etc. some things serve a functional purpose, but there is a lot out there that is just around to make $$$$$.
im not really a hardcore diyer, but if you can get exactly what you need and do it cheaply by doing it yourself (oh, and it is relatively straightforward), then why not. it only adds to the fun and interest in your system have one ofs.

As far as the cost, just don't forget that most people won't have an old scrap bookcase lying around for the wood.

yeah, true, but you should be able to pick up enough wood for $20 or less. so that would put it at $40 total if you had to buy the feet and felt and glue.

Sorry if this was mentioned already, I admittedly didn't read this thread the whole way through...BUT... I own an Auralex GRAMMA and I posted a review of it in another forum. I bought it for all of $50 from Sam Ash. I don't know exactly where Wayne got his pricing from. For the money, it does its job exactly as Auralex describes it. No fuss, no muss...

Is this what you are looking for?
http://responseaudio.com/sistrum_platforms.htm

Just kidding, I use a couple of large rot-iron potted plant stands.