This t-shirt spells out "Hate" until you see it in a mirror, then the same cleverly formed letters spell out "Love". I don't know if this t-shirt is for sale or merely conceptual/art, but I think it's terrific.
Update: Alex sez, "That shirt was
designed by Rachel Plefger."
Update: Khurram sez, "they're based on a form of writing called 'ambigrams', which appear to say one thing forward, and another thing when read in a mirror."
Update: David sends us this clever Love/Hate optical illusion tee