Source IP as an identifier is a really bad idea. As an example, I work at a company with hundreds of thousands of employees. Do you know how many internet IP'

Source IP as an identifier is a really bad idea. As an example, I work at a company with hundreds of thousands of employees. Do you know how many internet IP's we NAT them all behind? 2. Also, while most ISP's don't assign customers new IP's frequently, they do do it occasionally. (At least, Comcast in Denver does). I finally signed up for dyndns because I got sick of not being able to access my home machine from work every 6 months or so. OpenID/Facebook connect (like another poster suggested) would be a good choice, but source IP as a login identifier? That's just plain dumb.