I'm aware of at least two companies currently marketing a wide variety of lens adapters: Fotodiox and Rainbow Imaging. I'm not going to list everything they have available, but they have adapters to put almost any lens mount I've ever heard of on almost any other film or digital camera, and I've even seen reasonably-priced tilt/shift adapters for Nikon or Canon lenses on micro-4/3 cameras. The list is almost endless.