Kowa Six: When wandering through a pawn shop, I saw a Kowa Six sitting on the shelf. After a little haggling, I got a bargain price on the camera and gladly liberated it from their store. Kowa cameras were made in the 1970s and early 80s, and have sometimes been referred to as "the poor man's Hasselblad". The lenses are quite good, and still are sought after by photographers. For those looking for low cost medium format SLR's, Kowa offers a solid option.
    The Kowa Six is a standard all-manual SLR camera with leaf-shutter in the lenses.  It also offers interchangable screens and viewfinders, and 120/220 capability. As has been reported, the only potential problem with the Kowa Six and 6MM (which adds multiple exposures and mirror lockup) is that the advance gearing is soft and can strip if used too roughly, much like the earliest Bronica 6x6 cameras. I haven't had problems with mine, but I use the knob rather than the crank to advance the film just to help guard against problems. The 85mm lens I have is quite good, and lenses are available from a 30mm fisheye up to a 250mm telephoto. Another advantage to Kowa is that lenses are relatively inexpensive compared to current lenses from Hasselblad and other current manufacturers, but still provide excellent performance. Overall, I enjoy using my Kowa Six and will probably keep it as a 6x6 camera for occasional use.

Older Folding/Box cameras: One recent addiction of mine has been old folding and box cameras. I currently use a Ansco Titan (6x6, coated 90mm lens, 1/2-1/400 plus B and T), Zeiss Ikonta C (6x9, uncoated 105mm Novar-Anastigmat, 1/25-1/100 plus B and T), and a few old box cameras (Zeiss Box Tengor with coated Goertz lens, and an unnamed box camera - probably Kodak). With no built in meters and less than accurate shutters/optics, these cameras aren't exactly what you would consider for truly serious photography. However, with their compact size and use of 120 film, you can often make good quality 8x10 prints. Another great feature of these cameras is that they are cheap, and very portable. Rather than carry around a junky 35mm P&S, I have one of these folders with me as a carry-everywhere camera, and have caught quite a few interesting images while skiiing without concern for the camera's safety (most of these cameras cost less than $40, and are easily replaced).
     Since these cameras can be found relatively cheaply and use 120 film, they also make for excellent introductions to medium format without spending $200 or more on a good TLR. Those with coated lenses are definately preferred, and will offer reasonable color performance and sharpness. For those shooting only in black and white and keeping print sizes at 8x10 or less, these old folders can actually be exceptional bargains as the quality in such small prints comes reasonably close to much better cameras (provided your folder has a decent lens - like the Agfa Isolette or the later Zeiss Ikonta's with Tessar lenses). These cameras also have a "fun" factor similar to the Holga and Dianna cameras, but with a real lens and without the light leaks! Even for those firmly entrenched in a modern medium format system, I encourage people to pick up one of these old cameras for the fun of it.