Tweetburner is another tool for social media measurement
Just a quick heads up: Similar to the Cli.gs service is Tweetburner. So far I’m finding that Tweetburner has a prettier interface with charts and all. Also, it has my requested “time of day” style reports. So you can start to learn when people are paying attention to your Twitter posts It does give you a slightly longer URL though (twurl.com vs cli.gs) so if you need every precious character then perhaps Cli.gs is the better choice.