How can I create a single log-in and profile for a network of three sites using Django?
Depends on your server(s).  
Do all the sites have access to the same DB?  Then use dcrodjer's answer.
If not, you can implement a OAuth style Single Signon Service, that the other sites authenticate against.
Ex:
site1.example.com
site2.example.com
site3.example.com
siteN.example.com
Would auth against oauth.example.com
How can I create a single log-in and profile for a network of three sites using Django?
I have a network of three sites and instead of having the user create a profile at each of the three sites, I'd like the user to only need to register one time, and then be able to use all three.
Is there an elegant solution to this problem?