Do you mean programatically or not? You can easily view the users for a specific database in SQL Server Management Studio. Expand the node for the specific database, then expand the security node, then expand the users node. There you can see the users for that specific database. if you right mouse click, and select properties, you can view the permissions for that specific user.
Does this help?
Scott Klein
Author - Professional SQL Server 2005 XML
http://www.wrox.com/WileyCDA/WroxTit...764597922.html