Tweetrush is based on the rushhour engine and aims at providing information on the volume of tweets that are sent every hour of the day. At the present 800,000 tweets are sent a day. That’s an average of 33,300 an hour. I only tweet at about 86 (not 200) a day depending on conversations.
You can see user’s tweet rate as well.
It’s a fun litle app that can help picture how twitter is growing at present.