Postcards, those that illustrators send out every 3 or 4 months really do work! I have been creating them and wondering if any ever made it to an art director's bulletin board or file cabinet. I would prefer the bulletin board of course, because you can really see 'though' a file cabinet to find our labors of love.
A little card I created over a year ago just brought me some work. I know this because the art director asked for the same style and wanted the dog added in to the piece.
So, do your best, send your cards, and keep sending them.