As far as I know, the absolute smallest is the Pentax *ist as szekiat mentioned. You can pair it with the 40mm f/2.8 pancake (it does cover full frame) and you'd have the smallest 35mm SLR kit with autofocus out there. As for the smallest 35mm SLR, I'd say it's the Zeiss Contaflex I and II. About the size of a Leica M with a 35mm f/1.4 pre-asph (tiny lens), but even a bit narrower.