Note: some of these things can be added to Windows, but by default, they’re not there, especially on other people’s systems.
* BASH. I think cmd has some similar functionality, but it’s much more complex, but forget the GUI when you want to do repetitive tasks:
for i in *.zip; do mkdir `basename "$i" .zip` && unzip "$i" -d `basename "$i" .zip`; done
How long would it take you to extract every zip file into its own directory using point and click? Again, I’m sure there’s a program, but I have it in BASH automatically.
* Multiple workspaces. Most window managers give you more than one virtual workspaces to put windows on, so you can unclutter and organize your desktop by putting applications or groups of applications on their own screen, then quickly switch back and forth between the virtual screens as needed. Multiple monitors, bah — who needs them?
* Moving and resizing windows with ALT + mouse. In Linux, I can drag around any window my mouse is under by holding the ALT key and click+dragging the window. I can resize it by doing ALT plus rightclick-drag. Sure, in Windows (and in Linux) you can move by dragging the title bar and resize by dragging the edges of the windows, and there’s even keyboard shortcuts for it. But it is so simple to simply hit the ALT key with my left thumb and have whatever window my mouse is in automatically be under my control without moving up to the title bar or over to the edges.
* Running an application by typing its name. The shortcut I created to bring up a Run dialog is the Windows key plus the R button. I hit that, then type the name of any program I have installed, and it runs — no scrolling around in a start menu or hunting it down in a file manager. Thanks to Linux having the good sense to place applications (or at least launcher scripts or shortcuts) in a set of directories directly accessible to your user (/usr/bin, /usr/local/bin), this simple way of launching programs is possible. (Course, this doesn’t count for programs that you custom-install, but you can always make a shortcut or launcher for it!) In Windows, I have to hunt down the program in the Start menu or find it in a sea of shortcuts on my desktop or quick launch bar.
* apt-get. Hunting a program down that can do something in Windows can be a hassle — not only do you have to search Google for it, but you have to make sure what you’re getting isn’t some malware of some sort that will steal everything you have on your computer. I trust every single package from apt that comes from my distro, and there are tons of them, a program for pretty much every purpose imaginable. And installing is as simple as typing sudo apt-get install [programname].
* Amarok. A music program that organizes your music, has playlists, can play everything you want, has a plugin system, can interact with music devices, has a huge list of internet radio stations, a music store, album art, tag editor, can fetch lyrics automatically from internet lyric sites, has integrated artist, album and song information from Wikipedia, and more? Not on Windows! One can only hope that once KDE4 becomes final, Amarok can be ported over, but until then, I have to make do with Winamp or Foobar 2000, which can’t do even half of what Amarok can do.
And of course, security and stability are a given.