I bought a Canon EOS 500N body (EF mount) and I want to also buy a Nikon N65 (F mount) camera. The question is if with this adapter I can use a lens for both cameras?
maybe you have some similar experience?
Yes, that adapter should let you use a Nikon F-mount lens on an Canon EF-mount body, including the 500N. I don't think you can find an equivalent adapter to go the other way (i.e. Canon lens on a Nikon body).
Please note the long list of caveats on the linked page: the lens will work in manual focus only (with focus confirmation), you need to adjust aperture manually, you may need to change aperture every time you focus, etc.
An adapter like this one makes sense if you've got a special Nikon mount lens that you'd really like to use on a Canon body for some special purpose, but it's not the way to go for everyday walking around.