Clearbit - Clearbit provides Business Intelligence APIs
V12 Data - V12 Data offers rich data sets with verified addresses and emails for personalized marketing campaigns.
DataXu - Marketing analytics for brands and agencies.
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
Amobee DSP - Cross-Channel Advertising
Google Audience Center - 3 votes and 6 comments so far on Reddit