We’ve been using the GLogin plugin in conjunction with the One Intranet plugin to control access for some of our clients who use Google Apps. http://wp-glogin.com/ This allows staff to login from anywhere. We’re looking at Active Directory options for another client but I don’t have any advice on this as yet.
Otherwise, we control access via IP address lockdown which requires no login to view the intranet, apart from VPN access from remote locations where required.
The profile link thats displayed when you visit your own Contact Card on the Staff Directory, is there a link that can be put into a custom menu item? so rather than them having to go through a long way to get to their profile, just add something to the menu?