Let me qualify this by saying that lately I have been enjoying a lot of MSTRKRFT’s stuff espescially the remix of Death From Above 1979′s Sexy Results and Justice’s D.A.N.C.E, but I think I finally figured these guys out.  At live performances they just use a standard DJ set with two turntables, MacBook Pro for Serato Scratch Live, and a DJ mixer.  In the studio, they use probably a lot more stuff, but most notably:

• very similar drum beats that are usually a variation of, or exact replica of kick, hat, snare, hat with some occasional fills.  Don’t get me wrong, it usually fits in very nicely, but it is seriously used in just about all their songs.
• usually has a simple driving loop on an analog synth, usually Moog-ish in tone, sometimes arpeggiated, sometimes not.
• short clips of sampled vocals, if any.

And yes, I do realize the above describes a fairly large quantity of music, but damn if MSTRKRFT hasn’t taken this formula and ran with it.  In fact, I am currently planning a track based around this formula, however many times it has already been done.