A festive holiday one:
Fuck Ireland
Celebrate St. Patrick's Day by stealing a leprechaun's pot o' gold and donating it to help suffering Japanese people.
US politics inside-joke:
Save Obama's Birth Certificate!
We fear the Japanese tsunami might have washed away President Obama's longform birth certificate in Hawaii. Please donate so we may attempt to retrieve it and finally prove he was born in Kenya!
Paid for by the Uncyclopedia Tea Party
My ham-fisted attempt at Aleister's suggestion:
GODZILLA!
Nintendo's Wii has awoken the sleeping giant. Please donate now to assist its victims.
Self-explanitory:
Think of the children. The creepy, souless robot ones.
Please donate to aid the Japanese after the earthquake before their technological abominations have a chance to take over.