I just came across this app over on the android.com forums. If you've been having issues with inadvertently turning your volume up, down or off without realizing it (easy to do with the side mounted rocker switch), then download this really great little app (called RingGuard in the Market). The way it works is to require a manual confirmation of a volume change before anything can be done. So if you are pressing the rocker switch without realizing it - you would have to manually click the "okay" button to confirm the change.
This is exactly what I've been looking for! I can't tell you how many times I've turned my ringer either down too much or completely off and missed calls as a result. That's all history now! Kudos for the guy that came up with this freebie!
He's made my life much happier! cuskit