San Jose-based eBay said Wednesday afternoon that it has acquired San Francisco-based StumbleUpon, in a deal worth approximately $75M. StumbleUpon develops a service that allows users to discover and share content online, through a browser add-on. eBay said that the acquisition will provide it with exposure to a fast-growing, community-based service with 2.3 million users. The three founders of StumbleUpon will join eBay as part of the deal. StumbleUpon has received funding from First Round Capital.