I don't know why I haven't mentioned my use of these here but it is only as of today with the addition of a new Def Tech SuperCubeI that made me think to share.

I use three Def Tech C/L/R 2300's across the front due to a whole wall of built-in cabinets. In case you don't know this speaker, they are primarily center channel speakers that can also be used as a vertical front speaker. Provides terrific matching and each of them have a 8" powered sub in them.

Because they sit on variuos shelves in the cabinet I needed to find some way to isolate them from vibrating the heck out of the whole wall which contains all sorts of other stuff besides audio/video.
Hence the use of SuperSpikes.

And today I added them to the new sub.
What an instant difference in the soundstage, the responsiveness and the tightening of the lows. Went way byond my expectations.
If you have never heard of them, here's a link to the US distributor.

http://www.taylorsales.com/SuperSpikes.htm

All I can say is they work particularly well as far as isolation is concerned. Frankly I can't get too crazy (well I can but...) about all the claims to use them under every piece of equipment. I just find they do what they say when it comes to speakers. They are especially useful since they are a "contained" spike. (look at the site for explaination) so work great on every surface.
Never heard them mentioned here but then again maybe I just missed it.

Finally, what a difference adding the sub to my system has made. I went with Def Tech rather then Outlaw only based on cabinet size. Would have loved not spending twice as much but that's the way the space dictated. I resisted for a long time and now the system sounds like I always thought it should.