mine is simply writing my name , i guess it's indication of my tendency to simplicity and just blurring out whatever in my mind
although as a teenager , i had a 'logo' that i always drew beside my name in signature (basically some bones and flowers forming a heart shape)
as for the forum signature , i change it like every two days or something ,usually it's a quot i like which if anything ,i guess it shows how moody i am heh