The title basically says it.
I want to switch fastly between windows without using the keyboard. How do I do that in Unity?
"How does Gnome 3 do it?": Gnome 3 has an active corner in the upper left (That was used by Unity to show the launcher earlier). It shows all windows on one screen, so you can select which you want to focus on.
Super + w
. Maybe the same key combinations can work in lubuntu. – Parto Mar 16 '14 at 15:09