contest or collection theme specific relevancy up/down vote system

To make it easier for future contests and general collection management allow the creator of the collection the option to add a theme, which would then put an extra +/- (or score 1 to5?) vote option for images added to the collection that people can vote for how relevant the image is to that collection theme. This can also then be also used as a contest/collection only voting system and for other similar tasks. What do you think guys?