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.
OSGi framework implementation in C.
Celix is an implementation of the OSGi specification adapted to C. It will follow the API as close as possible, but since the OSGi specification is written primarily for Java, there will be differences (Java is OO, C is procedural). An important aspect of the implementation is interoperability between Java and C. This interoperability is achieved by porting and implementing the Remote Services specification in Celix.
Apache Whirr is a set of libraries for running cloud services
Apache Whirr is a set of libraries for running cloud services Whirr provides: 1. A cloud-neutral way to run services. You don't have to worry about the idiosyncrasies of each provider. 2. A common service API. The details of provisioning are particular to the service. 3. Smart defaults for services. You can get a properly configured system running quickly, while still being able to override settings as needed. You can also use Whirr as a command line tool for deploying clusters.
Innovative Web framework based on JCR and OSGi
Apache Sling is a web framework that uses a Java Content Repository, such as Apache Jackrabbit, to store and manage content. Sling applications use either scripts or Java servlets, selected based on simple name conventions, to process HTTP requests in a RESTful way. The embedded Apache Felix OSGi framework and console provide a dynamic runtime environment, where code and content bundles can be loaded, unloaded and reconfigured at runtime. As the first web framework dedicated to JSR-170 Java Content Repositories, Sling makes it very simple to implement simple applications, while providing an enterprise-level framework for more complex applications.