stock footage at Beachfront B-Roll (for free) [UPDATED]
From what I could tell, there are at least 60 videos for download, probably more, and available “for any production purpose”. They range from :30 to 2:00 in length, and all very high quality; time-lapse, nature, technology, loops, abstract, etc...

I did run into a little bit of trouble.
The videos are not available for download directly from the site, but through re-directs to archive.org or to Uploadstation.com. This caused quite a bit of problems for me because iMovie would not import the only downloadable format that these movies are available from these site, as mp4. Because of the quality of the videos, I was determined to make it work, despite too many hours of reading through forums and message boards and not finding any workable solution.
Fortunately, all the videos are also online at the beachfrontprod youtube channel. The Easy YouTube Video Downloader add-on for Firefox allowed for download in .m4v format; problem solved.
Please check out their site.
[UPDATED 2/12/12]
I heard from the good folks at Beachfront B-Roll regarding the trouble I was having with downloading/importing video from their site.
MPEG Streamclip is a free software that converts any and all video formats to any and all video formats.
And courtesy of Beachfront, here are a few links explaining how to convert video for compatibility with iMovie/Final Cut using Streamclip:
http://chrisfenwick.squarespace.com/converting-5d-movies/
http://blog.vincentlaforet.com/2009/11/02/converting-that-h264-footage/
Also, Beachfront is uploading all their videos to archive.org, making access much easier.
