There aren't really any agencies that specialize in the adoption of Jewish children - I suppose thankfully there aren't a whole lot of Jewish children out there.
But here are a few ideas -
First try
http://www.users.qwest.net/~jcan/ - the Jewish Children Adoption Network. It's not an agency, but rather a networking group. (My blog post on this group can be found here
http://jewish.adoptionblogs.com/webl...option-network)
Try your local Stars of David chapter -
http://www.starsofdavid.org/
and try your local Jewish Federation or Jewish Family Services.
Good luck, and keep us updated!