By 13th level Bards can begin a Bardic performance as a swift action and presumably end one as a free action - so what about Inspire Greatness? It grants 2 HD and temporary hit points to go with it. Could a bard end and begin Inspire Greatness every round on his turn to 'refresh' those temporary hit points?
Covered here as well.
In summary: Completely legit. But it sucks up a swift action each round.
Great link, thanks for that.
I was thinking, for a swift action every round a Dervish of Dawn would effectively get +4 Attack and 4d10+Con fast healing. Pretty nice deal there.