One extremely cool programming project that you should check out is pGina. pGina replaces the authentication module on Windows 2000 and XP clients so that they can authenticate via SSL with an LDAP server. Further, pGina uses authentication plugins, so over time other methods can be used as interest determines them. The author was published in SysAdmin magazine. Read the article about setting up pGina here.
A tip ‘o the hat to the pGina crew. This is the coolest thing we can remember since Mandrake bought Bochs back in 2000 and made it Open Source.