http://bigdatastudio.com/2013/09/01/the-best-of-open-source-for-big-data/

Hadoop DistributionsHortonworks

Cloud Operating SystemCloud Foundry — By VMware

OpenStack — Worldwide participation and well-known companies

Storagefusion-io — Not open source, but very supportive of Open Source projects; Flash-aware applications.

Development Platforms and ToolsREEF — Microsoft’s Hadoop development platform

Lingual — By Concurrent

Pattern — By Concurrent

Python — Awesome programming language

Mahout — Machine learning programming language

Impala — Cloudera

R — MVP among statistical tools

Storm — Stream processing by Twitter

LucidWorks — Search, based on Apache Solr

Giraph — Graph processing by Facebook

NoSql DatabasesMongoDB, Cassandra, Hbase

Sql DatabasesMySql — Belongs to Oracle

MariaDB — Partnered with SkySql

PostgreSQL — Object Relational Database

TokuDB — Improves RDBMS performance

Server Operating SystemsRed Hat — The defacto OS for Hadoop Servers

BI, Data Integration, and AnalyticsTalend

Pentaho

Jaspersoft