There needs to be a term for this. http://www.journalscape.com/memory39/2006-06-27-19:37

The first four posts are very old. They are quite jarring now. It's not quite a ghost in the machine, this leftover internet presence that people are talking to. Notes at an online graveyard. The uncanniness is not helping. I've never been to a funeral, although plenty of people I've known have died, and this includes family. I've never actually been invited to one. I assume, however, that they are for the living, specifically to help get over the feeling that they're not dead. They're to ingrain a solid memory of saying goodbye. Something to stave off the thought, "I wonder how so and so is doing? I should go visit him." Maybe I'm the only one who does that, I don't know, and I make no claims on normal.

Still...there ought to be a term. Persistance of Memory39.