Tabs. I started to use tabs very recently. In short, you can group two (or any number, in fact) “windows” in one “big window”, by drag-drop of the window pane of one into another while pressing WK (usually it is mapped to using the middle mouse button, but I don’t have one, naturally). And switch from one to another indepently of the rest of the system. I use it among “related” tasks, for instance my Pidgin chat window and Firefox (or emacs and evince), this way WK+tab switches between just these two tasks, and if I want to go away (emacs, Nautilus… any other open window) I just alt-tab once and get to the next. Obviously there are also numerical shortcuts for any tab: WK+1 takes you to tab one, and so on. I know, the way I use it is more or less like Alt-Tabbing… but it doesn’t exactly feel the same: I don’t have to backtab. I will be using it more and more, probably as I love this feature.