"Silence isn't golden" getting old? How about a meta-diary with suggestions on how to announce those open threads?
"Because George W. Bush is still President."
"Exercise your Free Speech rights while you have 'em."
"Pimp your diaries here. On second thought, don't."
"Where O/T is OK."
"Which Republicans are you hating most today?"
"Open yer piehole."
"Let's start a Leftwing Noise Machine."