This topic came up recently in a parallel discussion board of the AHA. The SALALM (Seminar for the Acquisition of Latin American Library Materials), the organization of Latin American Librarians in the US, has developed just such a site for digitized Latin American manuscript collections:
I am teaching an Afro-Latin American History course and assign primary sources for each class. My students do not read Spanish nor Portuguese, so I rely on translated sources.
Your site has been very helpful. I created a much shorter list for myself and for my students and your site is on it. I've pointed it out to them as a place to get sources for their research papers as well. Thank you!