Topsy Social Analytics is probable one of the best free Twitter analytics tools. With Topsy Social Analytics, you can analyze domains, Twitter usernames, or keywords -- and they can be compared over four timeframes: one day, a week, two weeks or a month.
Each type of analysis returns different results. Compare three domains, for e.g., and Topsy analytics will chart the number of links it found to each. Type in three keywords (including names, as in the image at the beginning of this article) and Topsy shows how many times each was mentioned. And if you compare up to three Twitter usernames, Topsy shows how many replies/mentions each received.
After any search comparison, scroll down the page and Topsy shows the top links in the past 24 hours that're related to your comparison -- along with several data points that measure the performance of each link, such as influence, "momentum," "velocity" and "peak."
You also have option to tweet your search results or send the results as link. All of this is free. Topsy says an "expanded analytics offering" is in the works for later this year.
More Info: Topsy Social Analytics
[tags]search analytics,social media,social networking,social network,topsy,topsy social analytics,real-time[/tags]