Tumblr is getting more interactive. The site is testing Buy, Pledge, and Get Involved buttons that will be automatically added when users post content from Etsy, Artsy, Kickstarter, and Do Something. The buttons allow followers to make purchases or donate money without leaving Tumblr, and could in the future be expanded beyond the four pilot partners to amp up the e-commerce capabilities of the platform. According to Ypulse’s most recent social media tracker, 25% of 13-32-year-olds and 39% of 13-20-year-olds are currently using Tumblr. (TechCrunch)