I like the slip-on eye cup (little rubber thingie with a metal clip) that I have. But I never use it. I don't carry a camera with it attached, for fear of losing it, and when it's in my camera bag I forget it's there. If I put a camera _in_ the bag with the eye cup attached, it'll get knocked loose somewhere in the bag.
I keep meaning to use it more often.
-- Glenn
