For the Berklee Intro to Music Production Class I'm currently taking online, I chose one of the topics that I've known about, but never proved it to myself - Comb Filtering due to reflective surfaces nearby monitors and microphones. (You are reading this on one of those reflective surfaces right now - don't record vocals while sitting in front of your computer screen!)

Here is the YouTube for it:
http://youtu.be/0IV7YAoIGAg

And I also exported the sound capture that I did while making the demonstration. It's at this soundcloud link: http://snd.sc/1d1zBKh

Yep, the physics do actually work! Whew!

-Scott