I seek Open Source Java projects for contribute.
BBCT is looking for developers. If you are interested in contributing to a baseball card collector's app, register for our mailing list and introduce yourself. You should also fork our GitHub repo and take a look at the developer documentation and the list of open issues. We look forward to hearing from you.
We are developing premium mind map / knowledge management application helping many students, researchers, writers, projects managers etc. (however it uses pretty old technologies namely Java, Swing, OSGi). Look at http://freeplane.org/, https://sourceforge.net/apps/phpbb/freeplane/viewforum.php?f=1, https://sourceforge.net/projects/freeplane/reviews and write a post to http://freeplane-developer.996965.n3.nabble.com/ if you like to get in touch.