Notifying users by e-mail their password is going to expire

http://theessentialexchange.com/blogs/michael/archive/2007/11/13/sending-an-e-mail-to-users-whose-password-is-about-to-expire.aspx

http://blogs.dirteam.com/blogs/jorge/archive/2008/07/20/notifying-users-by-e-mail-their-password-is-going-to-expire.aspx