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.
STV Voting Tools
Apache STeVe is a collection of online voting tools, used by the ASF, to handle STV and other voting methods.
Apache Olingo is a Java library that implements the Open Data Protocol (OData). Apache Olingo serves client and server aspects of OData. It currently supports OData 2.0 and support OData 4.0 (beta). The latter is the OASIS version of the protocol: OASIS Open Data Protocol (OData) TC. The extensions part of Olingo for OData 2.0 contains additional features like the support of JPA persistency or annotated bean classes.
Apache ACE is a distribution framework that allows you to centrally manage and distribute software components, configuration data and other artifacts to target systems. It is built using OSGi and can be deployed in different topologies. The target systems are usually also OSGi based, but don't have to be.
When assembling software out of reusable components, the task of deploying software onto an ever increasing number of targets is not trivial to solve. This becomes even harder when these targets require different components based on who's using them. Apache ACE allows you to group those components and assign them to a managed set of targets. This allows you to distribute updates and new components easily, while keeping a full history of what was installed where during what period. It also helps you setup an automated development, QA/testing, staging and production environment.