You want to be able to sort them in the post? What's stopping you from rearranging them in the post content?
Very easy to implement. IP2Location gives you 20 free lookups per day. Would be nice to be able to click the IP address on a users profile to see IP information. Should be quite easy to implement as a link.
http://www.ip2location.com/<IP ADDRESS HERE>
Would be cool, but I think this would be better off as a plugin due to the limitation factor.
@luke Not sure how you'd apply this as a plugin. If I knew that, I'll throw it together.