su2 is a great program for anyone that has anything to do with system administration. su2 gives you the ability to masquerade with the UID of other users. You use own password to switch. Probably the biggest benefit of su2 is that you retain your own customized shell environment. For the most part, this program is used by system administrators to become root, but su2 has been written to enable much more flexibility than this. Regular users can put a .su2rc file in their home directory to enable other users to become them. While this may sound odd, it is sometimes useful to allow a number of users to masquerade around with the uid of restricted accounts. One such example of this is a 'www' account which is a common occurance with the proliferation of the web. While the www user's password may be starred out to disable direct logins, root could put a set of user names into ~www/.su2rc to enable these users to 'become' www and do Web administration. [This feature can be disabled if you are worried about 'account sharing.']