- People do things at places. If you don't write a status message in your checkin (most don't), I can still sense what you might be doing. I try to write down what I'm doing at the places I check in at, mostly for historical interest later on. It's what Twitter should have been and was for a while, the “What Are You Doing?” social network.
- This social network tells me what people are reading (and watching and listening to, if the website has the right content type associated to it in the metadata).
Instagram (though I wish Flickr had wised up to it early enough, since Flickr does so many things right on a technical level that Instagram just won't do).Twitter
- You can follow bands and there's a feed. And you can buy their album for a decent price. SoundCloud would be here if they knew how to make money.
- The best place for the news. If you see someone saying “Why aren’t any of the newspapers covering [x]?” then stop looking to newspapers to spread the news. The news is spread on Twitter. I have real problems with Twitter as a medium and I think the format influences the type of content there, that is, it's not a problem of who I'm following but rather the incentives are for spreading memes, making jokes, overwhelming with news, not as a medium for calm reflection. Their API is the best in the business (Swarm's is actually slightly better, if less well-known).
- Only to look at my cousins' baby photos. I still don't know how to Facebook. I use it to signal my interest in events. People that put on events: list your event on Facebook.