Simian Mobile Disco

SMD (Slipmatt Dubs) is one of 3 aliases of UK born hardcore and happy hardcore DJ/producer Matt Nelson, who also goes under the name Slippery Project but is best known as Slipmatt. Is probably most recognised for the 1992 release "On a Ragga Tip" with fellow UK DJ John Fernandez (a.k.a. Lime) under the moniker SL2.

There is also a diy thrash band from Los Angeles, California named SMD. They are currently on Six Weeks Records and have released a demo cassette, 9 song 7" EP, an 8 song 7" EP, another demo cassette(this time with 17 songs rather than 5), two full lengths, and lastly, the recently released "The Devil Makes Me Do It"

SMD is also used as an acronym for Simian Mobile Disco, however the band have yet to release any tracks as SMD.

Recently, well-known hardstyle producers Noisecontrollers have adopted SMD as their alias for releases on the Scantraxx label. They have so far released only one record, which includes a remix of Krezip's I Would Stay and is a huge hit in the hardstyle scene.
In this case, SMD stands for Snuff Movie Diggerz, to which they refer in the as of yet unreleased track "All For The Thrill".