Assign multiple groups to a user

My problem is I am trying to make my Mac a web server, and I have having some problems with permissions. If I chown my web root to www:www (the user/group Apache is using), I cannot save my files to that folder under my main account. So I was wondering if I could assign the group "www" to my user (but also still be staff), so I could save files there. If there is another solution to this problem, I'd like to know.

Thanks,
Spencer