Tools for visualizing Twitter from Jeff Clark.
I recently came across Jeff Clark's portfolio, which features a ton of solid data visualization tools and projects, including a couple of nice applications for Twitter.
Twitter Venn (created using Processing and Twitter Search) takes a set of terms and creates a Venn Diagram showing the rate of tweets containing the each of search terms and combination of the search terms. Twitter Venn also shows a tag cloud for each regions with other common words. Look at the Twitter Venn for design, less, better: