twinfluence: enables you to discover if your tweets have an effect in twitterworld!
From their site:
I’m an automated system for measuring your twitter influence!
These resources are taken from Deltina Hay’s critically acclaimed book, The Social Media Survival Guide, already in its second edition. Social Media Power readers can get a discounted copy of the book from the publisher. Learn more about Deltina and her availability for speaking engagements at Deltina.com. You may also enjoy listening to her video tutorial series on YouTube.