I have a Nikon 500/8 reflex from 83-84 that I didn't use for years. When I bought it I shot Kodachrome 25 or Velvia (ASA 50), and only got good shots with it in bright sunlight using a tripod or monopod. With the stunningly better low-light performance of my D90 I've rediscovered what a useful lens it is, especially with it's close focusing ability (1:2.5). ISO 25 to ISO 200 represents 3 stops or 1/100 vs 1/800 in sunlight. This lens is now usable hand-held.
It also has a unique perspective for close-up work that will be fun to explore in the future.
I wonder if anyone else is rediscovering older hardware, now useful due to our newer, more advanced cameras. I now need a higher-end body that will meter with my AIs lenses.