This looks great. One thing that's a little annoying is how the vertical axis automatically scales to the range of the data. It makes it hard to compare peaks that don't occur within the same view range.
It's hard to pick the right aspect ratio without knowing the data beforehand, but you could make some reasonable assumptions about how spiky the peaks are. Given those assumptions, you could choose a fixed-height (say, 400px), and then adjust the visible time range if you still want variable-width. This would allow the chart to increase in size without compromising the aspect ratio.
Alternatively, you could use a responsive layout and just choose between two or three fixed sizes.
Very slick UX and very informative as well! I would love to be able to create custom topics, such as 'D3.JS' and generate timelines with top tweets.
Quick question: how did you obtain the real-time metric "# of tweets per hour"? Are you sampling to determine an estimate using the Search API, or do you have access to a proverbial "firehose"?
Really cool, any plans to add other data sources? FB might be harder, but I think G+ has a public search API. I see it's just a demo for now, but a dashboard view would be great as that "go-to source" for top breaking news.
If you can, please do the same for Wikipedia / SOPA.. it'll be interesting to see the difference in volume between tech media reporting and general outcry..
This would be great as a map and if people tweeted a certain hashtag, color the map according to their vote. You could really see what direction the twitter audience is leaning. this is a neat implementation though.