Just found this thread. I'll throw in a couple.
1976 MX125C. These are very scarce, somewhat rare anymore. This sits in my sun room.
1968 MZ 250 ISDT bike. They only made I think 134 of these over a two year period. Pretty rare I would say. I bought this years ago out here in the dezert. I have no idea how it ever got here but it did. This was just sold to a collector in Germany a couple of years ago.
Unusual? This is somewhat unusual. Mid 80's Husky chassis with a 380 CZ motor stuffed in it for the CZ World Championships. It was cool.