I understand aMember does integrate somehow with WordPress, Joomla, vBulletin, etc but is that just a one-off thing or could you create one universal username/password identity for each user for all possible scripts running on your same site? For example, if I had WP installed at subdomain blog.mysite.com, vBulletin installed at forum.mysite.com, and Joomla as well, will this program keep me from making my users have to register three times for access to all of these areas of my site?
If the subdomains you are referring to all exist on one server, yes Amember provides single signon capabilities across the various scripts. Today a number of existing scripts are supported, and the process of creating new integration is either opening a support ticket and having Alex and team build one or building your own.