The User Information List in SharePoint stores information about a user. That list can be accessed (if you're admin) via browser by navigating to/_catalogs/users/simple.aspx from your site e.g. http://www.beyondweblogs.com/_catalogs/users/simple.aspx
You can also programmatically access it and play around with it.
Details of that can be found in following posts:
http://www.beyondweblogs.com/post/Update-User-Profile-in-Sharepoint-Programmatically.aspx
http://www.beyondweblogs.com/post/How-to-retrieve-User-Profile-info-in-Sharepoint-using-C-code-API.aspx
1bbb95dd-774e-456c-a4b1-8a0a2a4a3bba|0|.0