Suspend and lock command

Ok, so you're used to locking your system with Super+L in Windows and you can't find a way to do so in Ubuntu.

Well compiz has feature which you can set a number of commands with a certain key binding.
Open a terminal and type ccsm.

Then, at the first command line type gnome-screensaver-command --lock and at the second one dbus-send --print-reply --system --dest=org.freedesktop.DeviceKit.Power /org/freedesktop/DeviceKit/Power org.freedesktop.DeviceKit.Power.Suspend. Go to the next tab (Key binding) and at Run command 0 grab the combination Super+L. Do the same for the suspend function at the second key binding (I've set it to Super+Ctrl+S).

And there you go. Lock and Suspend with a press of button (sort of)...