Authentication with cookies

Hi

I'd like to limit access to some resources on a site unless a visitor
provides their email address. If they do provide an address, I'd prefer
they didn't have to re-enter it every time they entered that part of the
site.

Appreciate suggestions as to how this could best be achieved.

My initial thought was to display an input field upon the user selecting the
link to allow entry of their email address. Submitting would then allow
access and would send a cookie to the visitors's browser. Re-entering the
page after this by selecting the link would search for the cookie and allow
access directly if it was present.

Are there any tutorials or articles that could solve this problem?

Thanks
David