Okay, so now that I'm done with my studies (graduated with an 8 out of 10) I've decided which projects to tackle this month.
First I'll start with modifying the userimages plugin to support default (pre-uploaded) avatars. I intended to build this for the app I made for my graduation, but didn't find the time to do it.
Second I'll work on Notifier. I intend to make it generic so it will work for comments, pm's and forums, but can be easily extended for other things. Where needed I'll update Cotonti's built-in email system to properly support rich HTML email. Notifier will support both plaintext and HTML email. Perhaps I'll also include some form of click-tracking into the emails, but I'm unsure about the added benefit of this feature. The new Notifier will no longer support sending PM's rather than emails.
Finally I'll continue work on the mobile theme based on jQuery Mobile, but I'm not sure I'll be able to finish it.
The REST API is an honourable mention, but I don't think this is what most people need right now.