I have a brand new Microsoft Ergonomic Keyboard 4000 which is very customizable via the Intellitype software.
I have set up the Zoom Slider so that it acts as a scroller instead of zoomer (google for details). I think you could also use it as a volume control.
I have the key with a "Home" icon set so that it sends a Win-Shift-S to toggle between "show all" and "hide all" in Zhorn Software'e excellent Stickies
. Before I did that, I was closing them, having to fish them out of the Stickies manager and then having to reposition them; or sleeping them, which kept creating duplicates; or I would roll them up, which can be done by double clicking the title, but they were still getting in the way. And Win-Shift-S a bit of a pain to enter. My repurposed Home key works perfectly, and I can't imagine opening up a web browser that way.
So what are your own favorite custom keyboard tricks for whatever keyboard you use? Maybe I can get some ideas.