I came across a link for a free online slide show service over at The Generator Blog that I thought some writers could use to have some fun with their cover art or photos from conferences, booksignings, etc.
To see how hard it was to use, I made a demo slide show with the cover art from the Darkyn books. I uploaded my own .jpgs, made simple captions and picked a stock song to play in the background. It took about fifteen minutes altogether. You do have to register with the site to be able to edit your slide show, but that's also free (although it seems to work fine on Blogger, this widget is really designed for MySpace users, and if you've got one of those pages they give you precise instructions on how to add it to your page.)
Once you create the slide show, you can use a remote link folks can click on to go to see it over at the Slide.com site, like this, or get the embed code to put the slide show on your web site or weblog, as I did over on the fiction blog here (the background music may not play on some browsers.)
It's not exactly a substitute for a proper book trailer, but I bet some of the more inventive, creative minds out there can figure out a way to make it work just as well. If you decide to use this widget make your own slide show, post a link in comments so we can see what you do with it.