I've found that developmental psych (like the UChi's HD program) if you pick the right program can be particularly interdisciplanary... In addition to Chicago, I'd look at some of the programs at michigan, because they have a program in "culture and cognition" in addition to a strong social science collaberation between women's studies and the social sciences (which helps with the general trend of interdisciplnarity) Also their social work school might help in this matter.
You might also consider the Human Development programs in College's of Human Ecology at Land grant schools. Cornell has a rather amazing one, but there are also.
One way to find interdisciplinary possibility is by looking for people who are doing interdisciplnary work that you're interested in, and then apply to work with them, regaurdless of the program. It could work...