A good one mentioned in the OP comments is deducing when people are on vacation due to their traffic usage (or rather lack there of). Also, we don't know what o

A good one mentioned in the OP comments is deducing when people are on vacation due to their traffic usage (or rather lack there of). Also, we don't know what other information may have been listed there. What if they decided to add your name and IP address to the graph?