If you have open tasks or bugs left, one possibility is to list them at https://www.mediawiki.org/wiki/Google_Code-In and volunteer yourself as mentor.
We have heard from Google and free software projects participating in Code-in that students participating in this programs have done a great work finishing and polishing GSoC projects, many times mentores by the former GSoC student. The key is to be able to split the pending work in little tasks.
More information in the wiki page. If you have questions you can ask there or you can contact me directly.