Via email, 'uffeberlin' submitted a hint about an interesting feature of the dock sizing slider that's very hard to describe but fairly easy to use. Basically, you can force the dock to exactly 25%, 50%, or 75% of its maximum size just by using the slider. The process basically involves moving the slider a bit, and then repeatedly clicking the mouse button on the slider itself until the slider stops moving. But rather than try to explain it, just watch this short movie:
The movie starts with a drag of the slider, followed by repeated clicks on the slider thumb. When you see the slider thumb blinking but not moving, it's being clicked on but no longer sliding -- it's been locked into one of the three chosen sizes. Another drag frees it up to move again, then the process repeats.
So why is this useful? Who knows; more than likely, it's got little practical value (unless I'm overlooking something obvious, which is always possible). Nonetheless, I thought it was interesting and though (perhaps incorrectly?) that it was worth sharing...

