If you are registered, you get access to the members only section, can participate in the buy & sell second hand forum and last but not least you can reserve your preferred username before someone else takes it.
I have posted a 35mm f/2.8 Zeiss Distagon for Contax in very nice shape on e-bay, just selling off a spare. It is an AE lens. The item number is 260044976909. This is a very useful lens. There is a low opening bid and low reserve.