I have been asked to do a website for a client where a user can login to their account to access restricted pages.

He would like to be able to accept or deny members by going to an admin section (already set up) and clicking accept or deny button (like Friends Request system on Bebo).

Anyone know how to do this or know of any scripts on internet to achieve this?

The simplest approach I can think of to accomplish all this, is simply installing phpbb3 or a similar forum system. This gives you user management, access management and administration tools for free.

All depends how customized the web page needs to be I guess, but using the basic framework from such a forum system may be a good idea in any case.