The ASF is made up of over 100 top level projects that 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.
Apache Deltacloud provides common front-end APIs to abstract differences between cloud providers.
Deltacloud contains a cloud abstraction API - whether the Deltacloud classic API, the DMTF CIMI API or even the EC2 API. Each abstraction API works as a wrapper around a large number of clouds, shielding users from their differences. For every cloud provider there is a driver "speaking" that cloud provider's native API, freeing you from dealing with the particulars of each cloud's API.
Common components for Apache Batik and Apache FOP
Apache XML Graphics Commons is a library that consists of several reusable components used by Apache Batik and Apache FOP. Many of these components can easily be used separately outside the domains of SVG and XSL-FO. You will find components such as a PDF library, an RTF library, Graphics2D implementations that let you generate PDF and PostScript files and much more.
A modular, full featured XMPP (Jabber) server
Apache Vysper aims to be a modular, full featured XMPP (Jabber) server. Vysper is implemented in Java.