Joe Greenstein has served as a strategic limited partner at Four Rivers Group. He is also a partner at Very Serious Ventures. He co-founded and served as CEO of Flixster. Prior to Flixster, he was a member of the startup team and director of product management at Edusoft, a web-based curriculum and assessment platform for public school districts used by more than 4 million students nationwide. Edusoft was acquired by Houghton-Mifflin in 2003. While still a student, he co-founded CoreMetrics, one of the leading providers of real-time web analytics, which was later acquired by IBM. He was an advisor at fbFund REV. He is also a board member of Change.org and Juvo. He is also an angel investor. He has also served as an advisor to Xapo. He co-founded and served as an executive at Innerspace Labs.