SF-based ShareThis, a provider of tools to help users easily share content, has raised a $15 million second round from Draper Fisher Jurvetson. The funding brings its total to $21 million, as it raised $6 million last year from Blue Chip Venture Company, Illinois Ventures, DFJ Mercury, Queen City Angels and RPM Ventures. The company offers a button that can be placed on a webpage or in a user’s browser that a user can click on to share content quickly with a friend. It claims to be growing at a 50 percent clip per month—although there’s no mention of the size of the base. Funding will go towards general promotion of the service. Release.

-- David adds: In a brief conversation with Tim Schigel, ShareThis’ CEO, he said the funding will go towards enhancing its offerings for Google (NSDQ: GOOG) OpenSocial and for larger web publishers it hopes to attract. He said that ShareThis’ tools are currently being used by “tens of thousands of sites.” The company is also in talks with Facebook about being added to its site. Schigel, who was one of the founders of Advertising.com., spent 10 years on the venture capital side for 10 years, working for ShareThis backer Blue Chip Venture. He left the company in August to join ShareThis.