While Yelping, I was presented with this great example of a use of portable identity.  It simply allows you to use Facebook to populate the form field - that’s it.  Why don’t more sites do this?  Allow me to sign in to your newsletters or CRM programs using Facebook, Google, or others…  this usage should be much more prevalent than it is.

http://www.aviary.com/creation?fguid=8d2120f4-317e-11e0-b490-1231390ec091