Does anyone use wood for vibration control?

Its probably true that wood vibrates.  Some less than others though, and purpleheart perhaps less than others.  And it may be that the resonance of wood is easier to live with than of other materials.  An excellent material for damping is something that Marigo is now fabricating. This is what they use for their IT platforms, i.e., isothermal platforms.  Not super cheap, but under my  upper range open speaker baffles they are extremely effective.  I believe Marigo suggests using this material for components is just as effective.

Check out Mapleshade’s VCS Vibration control systems and racks. I find them very effective. I use their 4" thick maple VCS under my turntable and it made a very big improvement. Also have a 2" under my amp. I’m sold. But it is a system. You need to use the whole system with the brass feet and ISO Blocks to get the full effect. You can use them without the brass feet and it's quite good but better with them. Sure wood vibrates but it also will absorb and dissipate energy when used correctly. And yes it needs to be thick. 3/4 shelving is not thick enough. The thicker the better. Maple seems to be the best. Just try to get a 4" thick slab of maple to resonate like a thin shelf does. Metal, stone and glass ring and do not absorb or really dissipate energy like thick wood, instead they reflect the energy back into the components. Sure nothing is perfect but we have to set our equipment on something.

The entire building is vibrating. So, even if there were a material that didn’t vibrate much the component on the rack or platform would still be vibrating, right long with the entire building. Thus, the theory that wood is no good because it vibrates doesn’t hold water. The trick, gentle readers, is to decouple (isolate) the component from the building AND use very hard cone materials, I.e., not wood or carbon fiber or even brass, underneath both the component and the iso device to allow “residual vibration” to rapidly exit stage left. Cryogenically treated heat tempered steel would be a good place to start.

Sound is nothing but vibration within the bandwidth of the ear. So, you want materials that don't resonate at those frequencies.  

Hell the Earth is constantly vibrating and ringing from earthquakes etc. It’s a matter of degrees really. It seems all of audio is managing vibrations.

Mapleshade’s footers are not cone shaped because cone tips can resonate at the wrong frequencies. They are cylinder shaped with a shallow point instead.
You will get lots of opinions on this as with most topics. This comes down to tweeks really. In the grand scheme of audio things it is better to get the bigger issues of equipment synergy and the room/speaker setup dialed in before worrying to much about fine tuning with racks and cone and such. The exception being for turntables. Very important to have a good support under a TT.