This document discusses Gilt Groupe's use of MongoDB for real-time ecommerce analytics. It describes two key uses: 1) capturing product page view data in real-time to calculate scores to determine which products to feature, and 2) using Node.js to capture site traffic data and visualize it with Hummingbird. The system captures data, runs map-reduce to analyze it, and updates transactional systems to improve conversions and optimize product promotions.