Most coffeeshops are set up to be anti-social. Unless a girl I like is sitting next to me, there is very little chance there will be a conversation that leads to sex.
I have a solution:
My coffeeshop has only one table that everyone sits at (to encourage interaction). Also at each chair there is a console which has a numbered button for every seating position at the table. If you like someone at the table, simply push the button. Nothing happens unless that person pushes your button as well. Once a match has been made, a signal goes to the staff who comes out, makes an introduction, and gives a free chocolate chip cookie to everyone. And two hours every day, all electronics must be turned off or silenced. No laptops, no bluetooth, no cell phones. Only books, artsy crap, and musical instruments.
Even the trendy losers would eat this up because it’s kinda like myspace but with less attention whoring. Only problem I see is people abusing the matchmaker system to get free cookies.