Youtube is just an endless wonder to me. I wanted to find the music from my favorite DDR song, and realized that that was a good place to look. Since I couldn't remember the name at the time, I put in the original artist and one word of the name, and was able to get the whole name. Then I put in the whole name and DDR, and I find this, this, and (especially cool) this.
Our kids were very amused at the chicken dance over the weekend, and my wife ran into this mashup of the chicken dance and the macarena.
I was never a big fan of the old Pink Panther cartoon, but it did have one episode that I really liked, and I lost my tape of it (one of the very few things I've owned on videotape). But it occurred to me that it was probably there, and - what do you know? - it was.
We wanted to distract our kids for a few minutes with the Sound of Music's puppet show? No problem. (And, incidentally, as proof of that movie's power: I showed it to my kids, and even my 18-mo kept quiet until intermission. I wouldn't have guessed anything would keep his attention that well.)
Related to Sound of Music, I went looking for Oh, Susanna, to play for my daughter, and we found the scene out of the German inspiration for it. I wasn't even aware of the existence of that movie. Now I'm looking for a copy of it (preferably subtitled, as my German is not remotely close to what it once was).
And all of that, of course, is just stuff that I (or my wife) found in normal searching. I'm not even going to talk about the things you can find via 'Related' videos, starting from a known point. Way cool stuff.