I found this utility useful for those who want using messenger often, but annoy by messenger blink alert when people trying to contact you while concentrate on some serious task.
This tools call Desktops which release as v1.0.
Desktops allow you to create up to 4 virtual desktops which in this case you can sign in your messenger in one desktop but put your concentrate task another desktop, so you won’t be annoy by the alert while you are concentrate on some task, when the time you want to check your messenger message, just switch the desktop by pressing shortcut key.