Craigslist.org. Post a free add after setting up a special mail account at mail.com. Oh and ask for a phone number and a photo and, to defeat the spam bots demand that there be some mention of some word in your ad. Or go to a rock concert. That is the quick way. It seems to me that most younger american women are about a six pack away from trying bi.
I don't think you really need the six-pack. I believe that about 80% of women would take a trip on the opposite side of the tracks if they were just put into a situation where they could do it without being embarrassed/found out, etc.