Most forums have this feature, namely Zetaboards and Invision. I'm not entirely sure why we don't have this feature, but it's really nice to be able to see who's viewing a certain forum / thread for all of us stalkers out there who are all like, "OH MY GOD SOMEONE IS LOOKING AT MY THREAD"

Or is there a reason it's not implemented? ^^; If it helps, I found this here:
vboptions > thread display > show users browsing threads
Of course, it also depends on what everyone else thinks, if this is a good idea or not. x]