Many people are leery of switching to Linux because they believe there's a lack of usable software. However, as a Linux user, I actually seldom feel envy for the software available on other platforms. In fact, I'm quite hooked on KDE, and definitely feel its absence when I'm in some other environment.
Well, the other day I actually felt envy for OS X users. In my copious free time I could hack up a large subset of this functionality myself, of course, but right now, OS X is the only place this software exists.