The barriers to entry for professional-level photography are getting smaller all the time. Literally. It used to be that the trade-off for the best quality images was added size and heft to your camera body. Professional shooters have historically taken pride in their physically substantive hardware-- strapping on a DSLR as a sign of dedication. In late 2008, though, that paradigm shifted with the introduction of Panasonic's Lumix DMC-G1, a camera that fit the big image sensor of DSLRs into a compact body by getting rid of the mirror system that occupies so much space.
Since then, a new class of Mirrorless Interchangable Lense Cameras (sometimes called MILC cameras, or "micro four thirds" cameras, or "compact system cameras," or "Digital Single Lense Micro" cameras. No one's settled on a name yet, give it time.) have taken the photography world by storm, ushering in a new era that promises the best of both worlds: DSLR quality images at half the size and (often) half the price.
Panasonic, Olympus, Sony and Samsung are leading the charge, but DSLR stalwarts Nikon and Canon are widely rumored to be getting in the game soon. With adaptors that can equip them with any of your finest lenses, mirrorless cameras are setting a new standard.
The five entries listed here offer the state-of-the-art in the new camera class... all for less than six bills.