Under Leopard the "mind-of-its-own" sleep behavior of my WD MyBook wasn't quite enough of a nuisance to prompt me to look into it, since when asleep the drive would wake up only when it was needed. With Snow Leopard, however, this changed; it was spinning up and "beach-balling" the system upon all sorts of user actions seemingly unrelated to it. (For instance, I recall first noticing this shortly after upgrading, when it spun up when I launched Dictionary.app.) Thus it went from being an occasional, predictable annoyance to a frequent unexpected one. A bit of research led me to your applet, which works like a charm. Many thanks.