In lenses, I have a Hermagis Eidoscope that's about a 12" fl, f5, with waterhouse stops. Not exceptionally rare, but it is in outstanding condition, including having the original flange. Camera-wise, I think the W. Watson & Sons 12x15 is probably the rarest, with a close second the museum-quality Gundlach Wizard 11x14. The Watson is probably the rarest because of A: the age (1880s) and B: the size (12x15 was an uncommon size, even in that day and age - that's one HUGE camera to haul around). On the modern end of things, my Canham 14x17 is relatively unusual because of the size in the first place, and also because I personally know every person who's ever owned it, including the manufacturer. When it leaves my hands, that string of continuous ownership will be broken, no doubt. Now if we're talking about photographs, rather than cameras, I have a couple of nice pieces in my collection. A Eugene Druet photograph of Vaslav Nijinski, a large (12x18) portrait of Teddy Roosevelt by Pirie Macdonald, a Navajo man by Carl Moon, a Tom Bianchi artists' proof, a Hugo Brehme photograph of Popocatepetl (a Mexican volcano near Mexico City) and works by a number of friends of mine hanging up on the wall. And then there's the Andrew Melrose painting I got at an estate sale that the sellers were too lazy to try and read the signature on the canvas. Melrose was a Hudson River school painter, and one of his landscapes is in the collections at the White House.