The VideoLAN VLC Media Player is my favorite tool of the moment. Not only is it a great cross platform device that you can use to rip, stream, save, and convert video for different classroom applications. For example, I used the VLC Media Player to rip and convert a video clip from a promotional DVD sent to the jr. high to play on our digital signage.
I found the VideoLAN Wiki's "HowTo" page particularly helpful in this regard, and there are a ton of other uses for this quiet, low-frills download.
