University of Saarbrucken in Saarland Germany seems to have a lot going on in this area. I'm probably spelling all that wrong. Also look for the LASER summer program that is in Italy each year. Finally, www.lambda-the-ultimate.org is a much better place to ask this question.
Disclaimer: I dont have a graduate degree or even a CS degree, but I have done language design and implementation. I doubt that you will find a program in language design per se. You should already know the mechanics of language implementation: parsers, code generators, virtual machines, etc. I think the design of general purpose languages has converged on a few design schemes: static typing like Java, dynamic like Python, functional. Granted that it is possible to make huge improvements in Java and other mainstream languages, I think it might make sense to pick an area where most languages dont do it right, such as concurrency, and graft it on to an existing language. Even if your real interest is in the design of languages, I think you need to pick a goal for all this study. Given that, any good program with one or more professors that are working in your area of interest will work for you.