As of May 2007, there were 111 micro-blogging sites in various countries. Among the most notable services are Twitter, Tumblr, FriendFeed, Plurk, Jaiku and identi.ca. Different versions of services and software with micro-blogging features have been developed. Plurk has a timeline view that integrates video and picture sharing. Flipter uses micro-blogging as a platform for people to post topics and gather audience's opinions. PingGadget is a location-based micro-blogging service. Pownce, developed by Digg founder Kevin Rose among others, integrated micro-blogging with file sharing and event invitations. Pownce was merged into SixApart in December 2008.