Wired magazine has a nice article from a few months back that is about how municipalities like New York City can use individual reports from lots of residents to identify problems and opportunities to make their city better. This idea touches directly on the georeferencing topic that we'll discuss later in the class. 

Link: What a Hundred Million Calls to 311 Reveal About New York

Here's a graphic from the article that shows the proportion of reasons people called 311 over the course of the day (averaged over multiple days, presumably):

On a different, but related topic, you can also check out a site that allows you to look at Twitter word usage over the course of the day. For example, check out a graph of hungry, breakfast, lunch, dinner over the course of the day, according to Twitter. Or, you can look at the use of words on Twitter according to the sex of the tweeter.