V12 Data - V12 Data offers rich data sets with verified addresses and emails for personalized marketing campaigns.
Crunchbase - Crunchbase is a platform for discovering industry trends, investments, and news about companies around the world.
Lotame - Make your data actionable, learn about your most valuable customers, improve ROI by targeting the right audience and increase relevance across screens.
CB Insights - CB Insights is a company database for the venture capital and corporate development community.
Google Audience Center - 3 votes and 6 comments so far on Reddit
Owler - Owler is a crowdsourced data model allowing users to follow, track, and research companies.