While I certainly don't advocate for doing programs for the sake of their prestige, I do understand that some programs are much harder to gain admission into, and have a track record of producing well-written alumni.
There are a great number of international programs, but because I only have knowledge of the main programs in the United States, I'll list a few.
Creative Writing Programs
The University of Iowa
Session I: June 12-25, 2016
Session II: July 10-23, 2016
This program is notoriously difficult to gain admission into, due to its portfolio requirements and small class size. Nonetheless, the seminars are very well-organized, and almost all of the alumni of the program go on to become accomplished published writers in their own right. There is also a strong correlation (according to past campers) of alumni matriculating to top liberal arts college and universities.
The Adroit Journal - Summer Mentorship
June 26 - August 5, 2016
This online program is only a few years old, but its alumni have gone on to win awards such as National YoungArts Winners, Foyle Young Poet of the Year, Presidential Scholars of the Art, Davidson Fellows, etc. The mentors are all extremely qualified - all prior students or writers with MFAs and BFAs in their prospective literary disciplines.
The program admission relies on mentors individually choosing mentees, so the process is not very similar to other selective writing programs. Nonetheless, it does allow writers to collaborate one-on-one with their mentors over the course of an entire summer.
The Kenyon Review Young Writer's Workshop
Kenyon College, Gambier, OH
Session I: June 26-July 9, 2016
Session II: July 17-30, 2016
This program is only a little more selective than IYWS, but it is equally well-organized and run. I have only heard praise for the program, and the alumni similarly go on to become quite accomplished writers.
Juniper Institute for Young Writers
University of Massachusetts Amherst
June 18th - 26th, 2016
This program is a little less well known, but comparable to the Kenyon Review's program. It is a weeklong program, however, so it is more similar to Breadloaf and other writing seminars than a comprehensive summer program.
Interlochen Center for the Arts, Interlochen, MI
Session I: June 25-July 16, 2016
Session II: July 17-August 8, 2016
Interlochen is a well-known boarding school for student interested in the arts. It is also known for its numerous well-accomplished alumni in all of its respective art forms. There are two separate programs offered - one for novel-writing and one for general creative writing. While not as competitive, the program is nonetheless very well-run and well-known for its excellence in tutelage.
CSSA Summer School for the Arts
California State Summer School for the Arts, Sacramento, CA
July 9-August 5, 2016
This program is primarily for California students, but it is well known within the literary sphere for being an excellent program in its own right. The competition for admission isn't as difficult as other programs, but its curriculum is still well-run.
Journalism
AAJA Journalism Camp (J Camp)
George Washington University
August 1-6, 2016
Although this weeklong camp is run by the Asian American Journalists Association, it is also aimed towards exposing all minorities to journalism. It is an all-expenses paid program, with an emphasis towards print and media journalism.
Princeton University Summer Journalism Program
Princeton University
August 5-15, 2016
This program is aimed towards students from low-income backgrounds, and offers an all-expenses paid program, culminating in the publication of a summer-long publication. The program is well-known and has garnered an good amount of press attention over the years.
Dow Jones News Fund High School Journalism Workshops
Unlike the other programs, these are a series of high school summer journalism workshops spread across the country. All are free to successful applicants, and result in the opportunity to submit pieces to the annual Dow Jones Summer Workshop Media Competition.
Medill-Northwestern Journalism Institute
Northwestern University
June 26-July 29, 2016
This is a well-known, if pricey, program for students typically involved or holding editorial positions with their school newspapers. It is consistently ranked among the top journalism programs in the country. The students are called "cherubs" and spend their summer researching and learning about print journalism.
Stanford University
June 26-July 3, 2016
This is a fairly well-known program run by Stanford students. It does not require prior experience, and students can expect lectures and seminars by professionals in the field, opportunities to conduct field research, and workshops for various journalistic techniques.
E.W. Scripps School of Journalism High School Workshop
Ohio University
July 13-16, 2016
This is among one of the shorter programs, so students don't go quite as much into depth with their workshops. It is mainly based on lectures and seminars. The Diversity Scholarship covers 100% of expenses, but otherwise, students must pay for the program.
There are actually quite a few programs listed here as well: For Students , Read All About It: Journalism and Media Summer Programs
Humanities
Telluride Association Summer Program
While the other programs have their own merit, this program has been known to be one of the most impressive programs for any high school student. Admission rates are incredibly low, and the process involves about 6 lengthy essays and an interview. The program itself is centered around discussions regarding a theme, chosen each year by the Telluride Association. It's not necessarily a writing program, but it is worth a glance.
