Kind of what Google was doing prior to Caffeine:
Bizosys Technologies* has built a sSearch engine whose index is on Hadoop and HBase to deploy in a cluster environment. Search applications by nature involve read intensive operations. Bizosys experimented with its search engine that involved use of latest hardware options, software configuration and cluster deployment provisioning.
Original title and link: Hadoop and HBase Optimization for Read Intensive Search Applications (NoSQL databases © myNoSQL)