Ah, antimatter, every sci-fi dreamer's WMD of choice (and, apparently, the US government's). It's a nebulous power, borne of energy released from radioactive nuclei, and a transient one: the rare airborne antimatter particle quickly bumps into its abundant mirror-image, the electron, and the two cancel into a flash of gamma rays. Harness the stuff, though, and half a gram will net you 20 kilotons of explosive power--the size of the bomb at Hiroshima. Frank Close, physics professor at Oxford and former head of the Theorietical Physics Division at the Rutherford Appleton Lab, just released an excellent book, aptly titled Antimatter, which explores the concept from discovery to Tunguska to weaponry; despite what the media/imagination leads us to believe, the acquisition and stability of enough antimatter to detonate any kind of effective bomb is many decades and billions of dollars in the future. [Editor's note: I retain the right to allow said (cynical) imagination to remain fertile on this issue.]
Anyway, Paul Dirac is credited with the discovery of the positron--the electron's antimatter particle--in 1928, and science hasn't been the same since; almost every TOE is based on ideas of supersymmetry and coupling constants, of particle counterparts and charged component fields. Remarkably, five years before Dirac's theory of the positron was proven accurate, another scientist, Dmitry Skobeltzyn, made the discovery without realizing it. During an experiment with a cloud chamber, a device used to see particles and their motions by examining their vapor trails, he noticed that some of the electrons curved "the wrong way." Voila: the first positron sighting!
Today's massive-scale particle-smashers and trail-monitoring equipment is essentially mimicking this primitive observation technique, and the possibility of discovering additional particles that "curve the wrong way" has many physicists (and bloggers) holding a collective breath while the LHC prepares to churn out data. To give you a (very abstract) idea of how particle tracks can yield mind-boggling information, take a look at a simulation of what detection of the elusive Higgs would look like:
Those squiggles and lines are particles scattering all over the place, briefly illuminating their existence, and matter-of-factly lending explanation to ours.