It started with Slashdot, then Ask Bossy (I've always been a closet Agony Aunt). From there it spread to commenting on news stories on news.com.au. So far, nothing sinister or worrying. Then, one day while driving to work, I heard a particularly stupid comment on the radio and the next thing I know, I'm looking for the 'post a comment' button on my steering wheel! Soon it was way out of control, and I've been wishing I could post responses to everything from billboards to peoples' bumper stickers.
I really can't wait until the internet is better integrated with the world around us. I've always been fascinated by the idea of reverse geocoding, in the extended sense of taking your current location and view direction, and finding locally relevant data to display. The end result would be sort of like real-life tooltips for your physical surroundings. I want to walk down a street, and when I look at a shop, I see an overlay saying "Today's specials: widget X for $75!". Or I look at a train station and the times and stopping patterns of the next three trains pop up above it. Or I'm meeting a friend in a crowded public space and they get a neon MMO-style nameplate floating above their head so I can see where they are (and they can see me) even round a blind corner. (This last one, you can do to an extent with Loopt on an iPhone).
And of course, imagine the opportunities for commenting on stuff! You could tag someone's hawaiian shirt as "tastelessly unneccessary". You could voice your opinion on, well, pretty much anything! Which, I guess, is the fatal flaw of all this - that most people don't have that much interesting to say. :/ And worse yet, they have it to say about everything, so any system like this would result in an incredible quantity of mundane crap. Still, with some kind of reputation system to use as a filter on it all (mass moderation, Slashdot style? Whuffie? Or even applying Google's PageRank to people en masse?) it could lead to some very interesting possibilities.