Peter Madden is correct when he posits that agencies (especially small ones) don't do enough to promote themselves - and certainly not at the level of work they do for their clients. We frequently find ourselves in this predicament, but I think the major culprit is simply the old "shoe cobbler's children" syndrome. We always put ourselves last. We always wish we had more time to do great work for our clients, so the last thing we're going to do is steal from our most limited resource - time - to promote ourselves.
That said, at some point it has to be done.