Rotate video 90 degrees in OS X?

Does anyone know of a free/cheap tool for OS X that will let me rotate video clips by 90 degrees? I have a little Exilim camera that shoots short video clips, and I'm perennially framing my clips in portrait, forgetting that the camera saves everything as a landscape-ratio AVI. I want to be able to open the clips, rotate them 90 degrees clockwise or counter-clock and save them again as AVIs or MOVs. Mail me if you know the answer, please!

OK, here are a couple of solutions for this:

  1. In QuickTime Pro: Movie -> Get Movie Properties -> Video Track/Size — then use rotate buttons
  2. Simple Rotate, an iMovie plugin

(Thanks to Matthias, Marc, Mike, Dieter, and David!)