Sad but true: in 3½ years at Google I never compiled a protocol buffer. I also never contributed directly to the launch of a consumer product on google.com. Making up for lost time at Twitter, though, in my first few weeks there I've done both.
Enter Google Replay.
Search for Bieber on Google Replay and it'll show you a chart of the volume of Justin Bieber tweets this month. If you wonder what the spike is on April 10th, you can drill down by clicking on the timeline, and then again, to individual tweets about the JB sketch on SNL. Pretty cool! See also: results for Chirp, the Twitter developer conference.
Puzzler: below is a chart showing tweet volume (from Google Replay) for a two-word search term over the last few months. Notice the pattern of weekends (green) and the anomaly (red). Name the search term.