A couple of comments on what I have already:

freeSSHd: I like that it will accept NT authentication, but I wish it would do group authentication, as it'd be nice to set it up to allow the local admins group.

UltraVNC: At some point they changed the server so that every time you tweak a setting you get a RunAs dialog, and you have to select the correct user to run as, which is not the default. This is a gigantic pain, but no other VNC server that I'm aware of does NT authentication. Also, they broke their video hook driver at some point. I've actually been considering revving back to a version that worked better.

If anyone has solutions for either of those problems, I'd love to hear about them.