There is an organization called A.T.I.M.E. - A Torah Infertility Medium of Exchange that is based out of the New York area. Although the vast majority of the work that they do is focused on infertility support, resources, etc, they are also branching out to covering the topic of Jewish Adoption. A.T.I.M.E., as an organization, seems to be very much affiliated with the orthodox movement, but I know that couples of different denominations have attended their seminars and programs. As far as their adoption services, the following is from their website:

ADOPTION SERVICES
We offer comprehensive resources for adoption along with a very exciting program, which will attract Jewish birth moms across the US who are hoping to find Jewish families for their babies. Alter Katz (917) 562-0002

Just as there are families that choose to adopt only children that resemble them in recognizable features, skin color or race, it is also not uncommon for parents to want to adopt children born of the same religion. I would say that most Jewish families do end up adopting non-Jewish children and then making the decision at that point as far as conversion, simply because - I suppose thankfully - there aren't a whole lot of Jewish babies available for adoption. If this is something you are interested in, I suggest you give A.T.I.M.E. a call.