Direct volunteers to the right projects
I just stumbled upon http://whatcanidoformozilla.org/. You basically click buttons until the web site suggests a project that overlaps with your expertise.
The code is free and we could easily use it for our projects. It would be great to have something similar, perhaps under https://www.torproject.org/whatcanidofortor/. A technical downside: it requires JavaScript.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information