Three years ago, my very funny colleague Jay Black penned a TV101 essay about the phenomenon of "channel drift." That's when a cable channel drifts away from either its original format or it keeps drifting from format to format. Usually you see channel drift when a channel keeps its name (like AMC) but not the format that gave it its name (classic movies).

But just because a channel drifts from its original raison d'être doesn't mean that it's making a horrible mistake. There are so many cable channels out there, along with online, mobile, and other viewing options, that a cable channel needs to change to survive. But they also need to keep the brand that they've built up over the decades.

So experimentation and change are pretty much a part of what most cable channels do. But some are doing it better than others. Here's a list of cable channels that have done a good job breaking away from their old formats, and channels that are fumbling the ball. I'll also mention shows that have survived the various changes, and if they're helping or hurting the current format.

I'm one of the many people who laments the "channel drift" that has affected MTV. A network that started out as, well, "music television" has clearly become "anything but music television." There's even a graph now on GraphJam the depicts how The Real World caused the downfall of MTV. The graph shows how the airtime for music videos has decreased as The Real World grew in popularity. Perhaps it should also measure how the cast of The Real World became more attractive and subsequently less intelligent.

The graph posits that by 2010 music videos will be nonexistent on the channel. Also, interesting is the rise of what the graph calls simply "other crap" that coincides with the rise of shows like The Real World and Road Rules. I assume "other crap" refers to shows like The Hills, My Super Sweet Sixteen, and Made -- shows that have replaced music videos in primetime (and replaced music videos with their incessant reruns in daytime).

Do you remember coming back from your first semester at college and running into a kid you used to go to high school with who decided to use college as an excuse to totally reinvent him or herself? Like he was the class dork and in three months he's all of a sudden a death-metal anarchist? Or she dated the basketball team (the varsity, junior varsity, AND the freshmen) and now she dresses like Dr. Quinn: Medicine Woman?

There was always something disturbing about it. Not so much that they had changed -- everyone has a right to change -- but because what they now were was different from the template you had made for them. When the universe doesn't act like you expect it to, you get uneasy; it's a natural reaction. I couldn't help but feel that way this week, when I watched A&E's new show Parking Wars.