Google hasn't announced their final selection yet for mentoring organizations, but I'm operating under the assumption that we will be. Given that, this is the time for people to start putting together proposals for student projects. The window is only about a week long, and is opens up in just a couple of days.
We've got mentoring volunteers from the JRuby, RoR, rubinius, ruby, and Xruby communities, so don't feel constrained to any particular field. On the other hand, projects that are liable to benefit the largest possible group of users are certainly going to get some extra karma.
If you're not a student, but have a great idea, feel free to toss it out for discussion. Who knows, maybe someone will pick it up and run with it.