The ASF is made up of more than 150 top level projects which cover a wide range of technologies. Chances are if you are looking for a rewarding experience in Open Source, you are going to find it here.
A network application framework
Apache MINA is a network application framework which helps users develop high performance and high scalability network applications easily. It provides an abstract, event-driven, asynchronous API over various transports such as TCP/IP and UDP/IP via Java NIO.
Java Common Components
Commons Lang, a package of Java utility classes for the classes that are in java.lang's hierarchy, or are considered to be so standard as to justify existence in java.lang.
The Apache Cassandra database is the right choice when you need scalability and high availability without compromising performance.
Linear scalability and proven fault-tolerance on commodity hardware or cloud infrastructure make Apache Cassandra the perfect platform for mission-critical data. Cassandra's support for replicating across multiple datacenters is best-in-class. Cassandra is in use at Netflix, Twitter, Urban Airship, Constant Contact, Reddit, Cisco, OpenX, Digg, CloudKick, Ooyala, and more companies that have large, active data sets. Cassandra provides full Hadoop integration, including with Pig and Hive.