PHP User Management Module

I need a simple user management module that I will integrate into a bigger project. What I need: - one signup page that allows the user to complete fields like: user name, password, email address, full name and few other details I will give to the selected coder later; - one login page; - one page to manage the account (where the user is allowed to change some of his details once he is logged in). For the sign up process the user must click an activation link received by email, otherwise the account should not be active. Only clean and well commented PHP code accepted. If this project works out well we will work together again on similar modules.