Electron accelerators are by far the most common. You undoubtedly have many in your home as a TV or computer monitor has in it a roughly 50,000 V electron accelerator. Accelerated electrons are also used by doctors (and dentists!) to produce X-rays for diagnosis and gamma rays to treat some illnesses. Beacuse electrons do not weigh very much, they readily give off light when bent and it is this property which is exploited to produce medical X-rays and gamma rays. It is also used as an aid in biological and materials studies at places like Argonne's Advanced Photon Source.
Electrons can also be used for high energy physics research. In a way similar to how protons can collide with their antiparticles (called antiprotons) and transfer some of their energy to new states of matter via Einstein's E=mc^2, electrons can also collide with their antiparticles (called positrons). Electrons have the advantage of being able to transfer all of their energy to new matter while protons, which are made up of other particles called quarks and gluons, typically can only transfer about 10%. Electrons have a disadvantage in they radiate light. While useful as a source of X-rays as described above, this makes it difficult to accelerate electrons to the highest energy while using the "traditional" circular accelerator. It has been proposed that the next electron-positron collider use two linear (that is straight line) accelerators. Each could be 10 miles long and attain an energy of 250,000,000,000 eV or 5 million times more energy than in your TV set.
The High Energy Physics Advisory Panel reported in 2001 that "The highest priority of the US program [should] be a high-energy, high-luminosity, electron-positron linear collider, whereever it is built in the world." The International Linear Collider or ILC is currently undergoing design at labs around the world. NICADD physicists are actively working on a number of aspects of the ILC in order to make that a reality, and to make the case that it should be constructed in northern Illinois. This includes detector R&D and designing new detector technologies.