Or you could just go around just asking random women to join you two. You will get slapped, rejected and yelled at 49 out of 50 times. But that 50th time is oh so special.
There are a few poly dating web sites in other threads. (We should probably have a sticky thread for poly dating and social websites.) You could also try to see if you have any friends that may be interested. Or join some social groups that exposes you two to more people.