My fave keyboard shortcut is the Alt+F2 launcher. This works almost the same on both KDE and Gnome. For other environments I do not know. For applications that I use a lot it's faster to call up the Alt+F2 launcher and type in the application's name than to wade through a menu. It's also great for little one-off commands where you don't really need to open a terminal. And you can launch terminals from the Alt+F2 launcher too.

How do you know the correct command to launch applications? If your menus hide the true application names (Gnome, I'm looking at you-- hiding stuff is not helpful) there are a couple things you can do. In KDE you can right-click any menu item, then click Edit to see the correct command name. In Gnome you have to hunt down the menu editor to find this information.

In Linux, the graphical environment is separate from the console. A very cool thing you can do is drop to the console while leaving your X session untouched by pressing Ctrl+Alt+F1. This works with F1-F6, because you get six consoles. Press Alt+F7 from the console to get back into the graphical environment. When you want to do some command-line work it's faster and easier to use an X terminal like Konsole or Gnome Terminal. But when X is horked, Ctrl+Alt+Fn gives you a way to troubleshoot and fix things without rebooting.

I love a three-button mouse, and I love right-click context menus. KDE is loaded with these, and some Gnome apps use them too. When you're stuck, try a right-click.

One of my most favorite features is multiple virtual desktops. I'll have work stuff in one, personal in another, and as many more as I need depending on what the day brings. It's a great way to keep organized, and unlike Windows Linux won't die of memory leaks from having a lot of applications open. The number of virtual desktops is configurable, and you can even name them.

My other favorite shortcut is the panel or taskbar, whatever you want to call it. On KDE the default is to put it at the bottom of the screen, and Gnome puts it at the top. Of course you can park them anywhere you want. You can populate these with all kinds of useful applets and application launchers, and unlike Windows you retain complete control and won't have to suffer the annoyance of cleaning up the crapware that installs itself there whether you want it to or not.

One more slick shortcut is the "Show desktop" button in the taskbar. On Gnome it's that little bitty icon on the bottom left. In KDE you may have to add it to the panel yourself. When you have a bunch of apps open this is your one-click shortcut to a blank desktop.