Well, as my pappy always sez… “A fool and his money soon part.” And in my case, that’s usually what happens. I bought one of these today:
It’s a Griffin Technology PowerMate and it’s basically a fully customizable scroll wheel/volume knob. Considering my Mac stuff put me without scroll-ability, this thing is a godsend.

The software it comes with is 100% customizable, and it’ll do different things depending on what app you’re in. In iTunes, it is a volume/pause/play controller. In Mozilla, I can scroll up/down and go back/forward without using the mouse. It’s cool to surf with two hands… pretty neat stuf!