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.
Object Graph Navigation Library
The Apache Commons OGNL library is a Java development framework for Object-Graph Navigation Language, plus other extras such as list projection and selection and lambda expressions.
Provides Support for Some Archive Formats not Supported by Ant's Core
This is a library of Ant tasks and types uses Apache Commons Compress to support additional archive formats like ar, pack200, xz and cpio.
Apache Shindig software is an OpenSocial container and helps you to start hosting OpenSocial apps quickly by providing the code to render gadgets, proxy requests, and handle REST and RPC requests.