Oatmeal Studios

Oatmeal Studios wants funny greeting card ideas.  They won't publish anything that's too mean or too specific, so think light-hearted and think general.  You can submit by snail mail, on index cards, or by email if you request their email formatting guidelines.  They want greeting cards for a number of occasions, including birthdays, retirement, get well, and anniversary.  The website doesn't list their payment rates, but it's been said by various writers that they pay $50-75 for accepted ideas.