The ASF is made up of nearly 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 distributed computing platform.
Apache ZooKeeper is an effort to develop and maintain an open-source server which enables highly reliable distributed coordination.
Apache Whisker assists assembled applications to maintain correct legal documentation.
Apache Whisker allows an application to models the licensing characteristics of the contents of its distributions. Use cases are auditing the model against the contents of a distribution, reporting on the contents of a distribution and generation licensing documents (LICENSE, NOTICE and so on) for a distribution. Whisker distributes tooling for the command line and build system such as Maven.
A Java implementation of State Chart XML
An implementation of the State Chart XML specification aimed at creating and maintaining a Java SCXML engine. It is capable of executing an environment agnostic state machine defined using a SCXML document.