In case you're new to Facebook or you don't really use it for anything other than to look at others' profiles, it has a feature called "checking in." When you check in, Facebook tracks down your location via your phone or computer's GPS and lets you indicate what venue you're currently at -- whether it's a restaurant, store, or concert. Your Facebook friends will receive an alert to that end on their News Feed. I hardly ever check in; I only do so when I know it'll likely lead to a compelling conversation of some sort. For example, many of my friends are movie buffs like me. If I check in saying I'm watching a popular movie at the local theater, chances are they'll reply with their opinion of the movie, assuming they've already seen it. When I check in at the ballpark, my baseball buddies will chime in saying they're watching the game at home, and we'll go back and forth as the game wears on. Unfortunately, I've notice...