I have a couple of ideas, but most importantly, my favourite projects to mentor are ideas that come completely from the student. So if you're interested in doing GSoC this summer, you are a student entering, currently in, or just leaving an institute of higher education, and are eligible, get in touch with me. You can find me via my Fedora Wiki profile page. Just use the email address there or join the IRC channel. I will not reply via comments on this post.
I'm willing to hear all ideas, so don't be afraid to submit them. If you don't know yet what you want to do, send me an email anyways, and we can talk over the possibilities. So bring it on.
In the end, i may not be your mentor, but we'll do the best to find you a mentor for your proposal.