Michigan Virtual University

As one of the largest virtual schools in the U.S., Michigan Virtual School offers more than 150 online courses, including unique courses like Chinese. 
http://mivu.org/

Oakland University Pre College Department

The Department of Pre-College Programs provides programs to middle school and high school students in the metropolitan area. The programs are designed to offer academic, social, career and cultural enrichment to students. The department employs university students as tutors, peer mentors and office assistants.
http://www.oakland.edu/precollege/

Center for Talent Development at Northwestern University

GIFTED LEARNINGLINKS (K through grade 12)
This program offers online enrichment, honors and AP® courses.
http://www.ctd.northwestern.edu/gll/

Midwest Academic Talent Search (NUMATS).
Started in 1982, NUMATS is a program of the Center for Talent Development (CTD) that offers above grade-level testing for high-performing students in grades 3 through 9. This Talent Search approach is an extremely well-researched and respected program model in gifted education.

The staff headquartered in Evanston works with many state liaisons, including Michigan, to offer a variety of programs. NUMATS ensures that students, parents and educators have all the information they need about academics, enrichment programs and distance learning. Eligible students, based on test results and NUMATS criteria, are able to attend advanced summer and academic-year coursework. The programs at various locations in Michigan can be found at:
http://www.ctd.northwestern.edu/program/numats