Radius Networks - Radius Networks offers mobile proximity technologies.
Lotame - Make your data actionable, learn about your most valuable customers, improve ROI by targeting the right audience and increase relevance across screens.
ROXIMITY - ROXIMITY is a mobile advertising platform that enables retailers and brands to send targeted, location-based messaging to nearby customers.
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
AltBeacon - AltBeacon is an open and interoperable specification for proximity beacons.
Google Audience Center - 3 votes and 6 comments so far on Reddit