Encourage companies to follow industry giants. Big companies advertise their innovations for good. Keep a categorization/blog of these ads will inspire others to innovate in order to receive positive exposure.
Campaigns on innovations are already being used by industry giants to connect with people by emphasizing how their companies innovations create an impact on society. Leveraging these efforts by using these as examples for other companies to follow will create a sense of competition. A competition for good.
A simple form of global communication, such as a blog, that tracks and categorizes advertising, design, marketing campaigns, or even press releases of companies regarding their social innovations will allow people to see what companies have done for the social good.
This collection becomes another form of advertising for companies (giving them incentive to continue to advertise their innovations, and continue to innovate), as well as provide a base for discussion and rankings.