Screw Mount or K-Mount? If you're looking for K-mount, the M-series lenses are designed to go with the smaller M-series bodies (but will work on the K-series as well). I have a 50mm f/2 M-series lens that's pretty small. There's also a 43mm pancake lens in K-mount that will work on the film SLRs, and it's even smaller.

I'm not familiar with the screw mount lenses, sorry I am no help there. I know there are adapters that can be used to put a screw mount lens on a K mount body, but I don't know if there are any that will do the opposite.