Measure Your Twittering

There's lots of tools out there to measure how well you're taking advantage of Twitter. There's also articles popping up and posts on Twitter about how to best leverage this channel.

My favorite tools right now are, if a little superficial, proving helpful. They are:

• Twitemperature
• Twitter Grader (great sense of humor)

How do you use metrics for your Twitter presence? What other tools are out there?