Excuse the unnecessary Sixth Sense reference, what do you do with social networking profiles of people that have passed away?
Social networking and online user profiles haven't been around long enough for this to be a problem yet, but at some point the major social networks are going to need to have a way to deal with profiles of those that have passed away.
This week, Facebook, which has a relatively new feature where it suggests that you to "make Facebook better" for connections that haven't been active asked me to reach out to a friend that had passed away more than three years ago.
LinkedIn did something similar where it told me people who had looked at the profile of the person that I was looking at at that time, were interested in the profile of another person that had passed away earlier in the year; this wasn't as bad as the Facebook use-case.
I'd argue both (but especially the former) are really bad user-experiences and as we try to do more with people social graph, there will be a need to, for the lack of a better analogy, garbage collect and clean up these profiles.
The easiest online solution is fairly obvious one: give people's connections the ability to vote on certain states of the person after a period of inactivity on the profile; when in doubt turn to crowd-sourcing. :)
Update: It looks like Facebook's thought of this already. :)