V12 Data - V12 Data offers rich data sets with verified addresses and emails for personalized marketing campaigns.
6sense - 6sense is a B2B predictive intelligence engine for marketing and sales.
Adobe Audience Manager - Adobe Audience Manager is a data management platform that integrates online and offline data to deliver a unified view of all your audiences
Leadiro - Seriously Smart & Live B2B Data
Google Audience Center - 3 votes and 6 comments so far on Reddit
ZoomInfo - ZoomInfo is a B2B database providing detailed business information on people and companies.