In another list I see that GNU has been accepted for Summer of Code and is looking for projects.
My own favorite ones regarding GNU Emacs have to do with beefing up the Emacs Lisp runtime and bytecode system. In particular giving proper callback information from bytecode (bytecode offset, mapping information from bytecode to line numbers). The bytecode decompiler I started, while it works on simple examples, I think I could get going in a much more solid and reliable way.
And of course on the elisp package side, realgud has always been hurting for help, multii-display windows in the debugger.
But enough about me. What is most in need of help in GNU Emacs that a summer student might reasonably make progress on?
Discuss the ideas here (please cc me since I don't regularly follow) and contact me offline and I'll forward the GNU contacts. (Or you probably can look them up for yourself if so inclined. I am not a coordinator, I am just a backup mentor).