One of the demanding aspect of server side OSGi is to reuse the existing classic jar files as bundles. The other aspect of the spectrum is to diagnose these bundles. Out of the lot BND (Bundle Tool) tool from Peter Kriens helps you to create and diagnose OSGi R4 bundles.
The key features are,
1. Show the manifest and JAR content of a bundle
2. Wraps a JAR as a bundle
3. Create a bundle from a specification and a classpath
4. Verifying the validity of the manifest entries
This tool can be used as a,
1. Command line tool
2. Eclipse plugin
3. Maven plugin
4. Ant plugin
You will find more information about this tool here.
Apache Felix folks has written a Maven2 plugin based on BND called maven-bundle-plugin to create bundles.
You'll find a really cool article on usage of BND is available here.