This month a company called ClickSharp marketing released a "white paper" (that's corporation-speak for "longish essay") on how one might promote a film festival using online marketing techniques. The use of the buzz phrase "long tail" is misleading; the essay doesn't really have anything to do with the long tail concept. The marketing advice, however, is spot on.
If you're a festival director you're probably already doing some of these things. Do your best to take note of the others and implement them in the way that best suits you. The white paper points out a number of online tools that have sprouted up in recent years that make previously difficult or expensive tasks (like hosting video) easy and cheap.
If you're a filmmaker, you should take a serious look at the ideas presented in the essay, substituting the word "film" for festival where you find it. It might seem silly to consider who your sponsors might be, but I just saw a film at Slamdance where, during the Q&A, the filmmakers mentioned that they'd secured sponsorship from Orbitz in the form of a handful of free round-trip flights. Orbitz got mentioned in the credits and Orbitz-logoed gear was featured prominently in a scene or two, but never to the detriment of the film. There are definitely ideas here worth considering.