As a webmaster,  being busy enough with emails and logins for websites,there is nothing more annoying than having to constantly search for passwords. To save me a lot of time and hassle looking for login information,it would be very beneficial to have my password sent to me in follow up mails.

One of the benefits of this would that members of your site will be less reluctant to visit due to the main problems with membership sites is the lack of user interest unless your membership site is facebook or twitter visitors will not be incouraged to return to your membership site.

Another way to incourage visitors to revisit you membership site,is to include a user name and password when emailing the members of your membership site.