A new company in the US called Lease your Body is building a business on leasing out it’s members to Advertisors willing to pay them to wear temporary tattoos.
Advertisors can browse the growing list of more than 2500 members and pay from $100 to $5,000 for 30 continuous days of advertising on one of six body parts (neck, forehead, forearm, upper arm, hand, stomach or lower back).

This comes after an online casino paid a woman $15,000 to have her face permanently tattooed with their URL.

Novel this is, and with the right person, in the right place, and with the right product this may make some sense. For most products and services, I think Advertisors would be better focusing on creating a story (consumer generated media) that consumers would voluntarily spread to their friends, who in turn may be inspired to try the product, and in turn tell their friends.