Does someone have a really good example of where this would be useful? The description is basically, "When this element exists, do something" but what is the something you'd do? If it's styling, that should be done in CSS. If it's event handlers, that can be done with `.live()` or `.delegate()`.

I'd also like to see some benchmarks to back up the assertion that this is faster. The DOM modification events are generally accepted as slow and it seems like this is leaving a handler attached for the duration of the page's existence.