I think it is going to be hard to find someone that has a list of all the ACNP programs. When I was applying the programs I was interested in were:
University of Miami
There are many others but these were the programs I looked into and was interested. I think that U of Southern California and University of Alabama also have ACNP programs. Hopefully others will add other programs but I suggest that you do some research on programs in which you are interested.
I would recommend looking at the link above for the American Association of Nurse Practitioners (AANP) or the Association for Critical Care Nurses (ACCN) for programs. The BestNursingSchools.com website only lists the programs that advertise on that site.
Not all NP schools have ACNP programs. Here in my own state of Virginia, there are 8 schools that offer NP preparation. Only two of these eight have ACNP programs.
AANP's wesbite has a link that provides a searchable directory of NP programs by track and by state. However, someone needs to alert this organization that their list is inaccurate. AACN's website does not have a link to a list of ACNP programs though they offer ACNP certification. It is quite true that there are not as much ACNP programs as say, ANP or FNP. Not all colleges and universities have the faculty and clinical placement resources to support an ACNP program.