I hear ya on the beards...I jump between phases.  I figure something more like a bar code or image that the iSight can easily recognize yet be complex enough for login purposes would be great. 

The breakdown is that the tool would could use the 'isightcapture' command (via http://www.intergalactic.de/hacks.html) with the program and have it active with the login. 

The authsight hack (http://www.zdziarski.com/authsight.tar.gz) , which takes a screenshot after an invalid login, works by tailing the /var/log/asl.log for invalid attempts.  Authsight would obviously not work for this purpose and could not be used. 

Maybe having a successful login attempt via password, then a check against an image prior to loading the rest of the OS would work.  It would login, though an application would prevent use until the image is verified. 
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