"Ehcache is the de facto open source cache for Java. It is used to boost performance, offload databases and simplify scalability. Backed by the Terracotta Server Array, Ehcache becomes a linearly scalable distributed cache. It is a schema-less, key-value, Java-based distributed cache. It provides flexible consistency control, data durability, and with the release of Ehcache 2.4, search by key, value and attribute indexes. "
As seems fitting the blog post is up on myNoSQL.