Last year, Tableau's Andy Cotgreave and Andy Kriebel started Makeover Monday, a weekly challenge where they post a data set and visualization to Twitter and attempt to create a new visualization, telling a new story or an improved version of the original. They discuss and critique the original, and, in under an hour, each individually create a new visualization. Readers are encouraged to use the data for their own versions and visualizations, with reader submissions featured and retweeted. The data (examples include 538 data about MLB salaries and market data from Business Insider) is presented as a Tableau file as well as an Excel file. To date, some 55 Makeover Mondays have happened. An insightful interview where Andy and Andy discuss the process can be found here