Redis

Redis is an open-source, networked, in-memory, key-value data store with optional durability, written in ANSI C. It's used by the Wikimedia Foundation to build the new event logging, revtagging and usertagging analytics infrastructure for product development and editor engagement experiments.

General

 * Official site (see esp. Introduction to Redis)
 * Getting to Know Redis (PDF)
 * Redis, from the Ground Up
 * Redis and Relational Data
 * Redis Cookbook (book; not great, but see ch. "Analytics and Time-Based Data")
 * Interview with Salvatore Sanfilippo (code-oriented but still useful)
 * Redis DB (Google Group)

Analytics

 * Redis at Disqus (their entire analytics platform runs on Redis)
 * Effective Web App Analytics with Redis
 * How YouPorn uses Redis (video)
 * Realtime metrics using Redis bitmaps

Tooling

 * redis-py is the library of choice for Python
 * Getting Started: Redis and Python
 * Redis and Python (presentation slides)
 * Resque for jobs
 * Redisco, a Python ORM for Redis
 * py-analytics (I haven't used this)

Miscellaneous

 * Storing hundreds of millions of simple key-value pairs (how Instagram uses Redis)