I think the majority of schools interview before handing out acceptances. However, Maryland usually has 2 recruitment days (I think in Nov & Dec) where they invite 40 people to each, and offer admitance to all those people. There is no interview conducted on these recruitment days, just tours and seeing the school.
I also remember hearing that NYU used to give out a handfull of acceptances without interviews, but I don't know if they did that last year.