OpenRefine is a free, open source power tool for working with messy data and improving it

Example code from Learning Spark book

YUI Compressor

Stream summarizer and cardinality estimator.

A platform for visualization and real-time monitoring of data workflows

A Java package to automatically detect anomalies in large scale time-series data

Twitter's collection of LZO and Protocol Buffer-related Hadoop, Pig, Hive, and HBase code.

Hadoop library for large-scale data processing, now an Apache Incubator project

Kite SDK

Example MapReduce jobs in Java, Hive, Pig, and Hadoop Streaming that work on Avro data.

A grouping of Apache Pig examples.

A sample maven-enabled pig project complete with example of unit tests on UDF using junit and pig scripts using pigunit.