Is there a site for finding “worthwhile” jobs, or should we build one?

I'm interested in the idea of a site which helps identify "worthwhile" jobs people may be able to do, if they feel a desire for such a job.

Since "worthiness" comes in different stripes and is a matter of opinion such a site might let users tag jobs with categories such as "scientific advancement" or "access to education" and then jobs could be voted up and down on those terms. Job seekers could then filter by their skills and areas of interest to find the "best" jobs for them.

Does something along those lines exist, and if not - do people think it would be valuable?