Having caught some Boston cold, I'm going through my 4th box of Kleenex tissues, and it occurred to me it's a perfectly contextual ad medium. The tissue sheets on the top could have some benign messages: bless you, get well. The mid-tier would promote nasal drops and cough syrup. The last few sheets could push life insurance. Call it progressive contextual advertising.
Of course, there's a company, AdPack, that already puts ad messages on tissues. Apparently, the medium is big in Japan and has its own wiki entry.