Facebook is widely used social network in whole world,So if you also use Facebook any login to your account to see any updates, Then you might open your browser login and check your friend request etc.
Facebook Desktop is a free app which brings Facebook to your Desktop.It works both on Mac OS X and Windows.It is a light weight app which sits on your system tray and keep showing real-time updates.
It shows updates regarding :-
New Story posted on your stream,
When there is activity in a post that you had participated,
New Friend request,
Someone Pokes you,
Someone sharing stories with you,
When you got Group/Event invite
It shows messenger style notification when any new item comes,It also allows you to Pause and Resume showing updates.You can choose which update you want to be shown on your desktop.
It’s a free app but you will need to have installed Adobe Air as it runs on it.