You can pm yourself if you check 'send private message' while you're logged out. You surely can add yourself to your friend list too but I'll leave any thoughts on such a use to you.
Edit:
C3PX said:
True story.
I am now being ignored by myself and ignoring myself, at the same time. Talented multitasking right there.
Wich means in other words: you've found your true yourself ! Congratulations! I'm almost jealous.