Ah, the lovely Page 3 Girls. More numerous than the Swedish Bikini Team. More topless than dembones after a long day in the fields of E2.
The Sun, a daily paper across the pond in jolly old England, decided to post beautiful models in their paper on page three in order to boost sales. Rupert Murdoch was the marketing genius/sexist who pushed the idea. Having a new photo spread every day helped push their sales higher with the male crowd, especially way back in 1969. The girls were pretty, but not nude.
All that changed in 1970, when Rupert was off buying some small government/island/collection of souls. Larry Lamb, the editor of the Sun, decided to have a Page 3 girl (Stephanie Rahn) appear topless. A big ruckus ensued, which helped drive sales of the paper to almost half-again their normal circulation. Rupert couldn't argue with success, and from that point on, Page 3 was dedicated to a beautiful topless model.
Some famous women who have appeared on Page 3 include Samantha Fox and Jordan. A few parlayed their appearances into a success career, while some revelled in their five minutes of fame. Samantha, for example, moved on to a short singing career.
There are stores and books dedicated to the Page 3 girls, and AllPosters.com has a section where you can buy pictures of the scantily clad or undressed Page 3 girl of your dreams.
Dimview notes that in Denmark the expression is "Side 9-pige" (page 9 girl). Not very artsy, and often not even very good looking, but hey, people still seem to like the concept :-) The paper is "Ekstra Bladet".