Technical overview of three of the most representative KeyValue Stores: Cassandra, Redis and CouchDB. Focused on Ruby and Ruby on Rails developement, this talk shows how to solve common problems, the most popular libraries, benchmarking and the best use case for each one of them. This talk was part of the Conferencia Rails 2009, Madrid, Spain. http://app.conferenciarails.org/talks/43-key-value-sto