Known Identity Selectors:

Windows CardSpace

Windows CardSpace is a standalone Identity Selector written by Microsoft.  CardSpace is part of the .NET Framework 3.0, can be installed on the following Windows Platforms:  

• Windows XP
• Windows Server 2003
• Windows Vista
  

To install CardSpace, download and install .NET Framework v3.0 from here  

CardSpace can be opened independently by opening the Control Panel, and by clicking on the "Windows CardSpace" applet.  CardSpace can also be triggered from Internet Explorer 7, and from Firefox, with the help of an extension (which can be downloaded here ).   CardSpace CANNOT be triggered from IE version 6, or from any earlier version.

XMLDAP Firefox Extension

Chuck Mortimore has written a browser extension that will run on any platform that Firefox runs on.  This is the best option for anyone on a non-windows platform at this time.  Note that this identity selector is not a standalone client, but runs as part of the browser.

To install the XMLDAP firefox extension, go to http://xmldap.org and  click the "FireFox Identity Selector" link from within the Firefox browser.

Ian Brown's Safari Plugin

Ian Brown has written a plugin for Safari Browser.  Note that this identity selector is not a standalone client, but runs as part of the browser. 

To install the Safari plugin click on this link and follow the instructions.