These, while regrettably small, are the most explicit I found; there is, though, a flickr group devoted to the subject, and with over 1000 pictures I haven't gotten through them all yet:
http://www.flickr.com/groups/betelnut_beauties/pool/ . As with the PNW story of "bikini baristas," there are claims of more revealing images out there somewhere, but given that the subjects are as notoriously camera-shy as Amsterdam's women offering themselves at windows...