For Arabic summer programs, both in the U.S. and abroad, two highly recommended links are:
The Middle East Studies Association (MESA) provides information about summer Arabic programs at https://mesana.org/resources-and-opportunities/category/summer-language-programs (currently being updated).
The American Association of Teachers of Arabic (AATA) also provides a wealth of information about Arabic programs at https://aataweb.org/language_programs.
Also useful is the Center for Advanced Research on Language Acquisition (CARLA) database of programs in less commonly taught languages at http://carla.umn.edu/lctl/db.