|Sliders are great. When you adjust the volume on your machine, who wants to type in a volume number into an input box or select "low" "medium" or "high" from a drop list? You just grab a handle and drag it along a range to set some variable. How can you go wrong?
Often, though, we run into the need to have a graphical range slider for super large spans of data where the screen real estate is very limited. The unplanned result would be a tiny slider that no matter how gingerly you nudge the handle, the data value jumps way too far. Check out the graphic on the left; even if I move the handle one pixel, the data value would jump 10,000. Bummer.
We try to give as much visual feedback to the users of these kinds of widgets as possible. An important visual cue for a tool like this is an indication of the direction of the turn. When cranking up, the + glows, when cranking down, the – glows. The arrow heads reflect the direction of the turn and all the while the numeric value updates. If the rate of change were variable depending on the duration of scrolling, then the + and – symbols could grow or shrink.