The Vice Chair should support the work of the Chair, according to the bylaws.
That makes a lot of sense to me. Our current chair is very engaged in activism, but it’s hard to stay on top of the nitty gritty, or working on bigger projects that help streamline activism.
Other than that, the question of what projects to work on is pretty open ended.
In my case, I worked on projects like:
de-pixelating our logo
making it simpler for people to engage via the website
migrating Yahoo! Groups mailing list and message archives