Creating this list for my future reference; I have not personally investigated all of these.
Any Topic
My Slide Rule – Searches the web for courses in any topic
University of Alabama Early College
University of Nebraska Online High School
AP Courses
Scholars Online (Classical Christian)
Keystone National Online High School
PA Homeschoolers Online AP Test Preparation
Thinkwell
Math
Elements of Mathematics: Foundations. Gifted math class for middle school.
Derek Owens (monthly subscription, Pre-Algebra through Calculus; Physics; Computer Science)
Thinkwell
English
HS College Bound – Shakespeare for High School credit. Also offers some high school planning courses. We have taken several of these classes, and they very good. Mr Speed is very engaging.
College Admissions Essay class from Brave Writer
Latin, Greek, Classical World
The Lukeion Project – Latin, Greek, and History and Literature related to the classical world. High School level. Fantastic, high quality classes and instructors. Our kids have taken Greek 1-3, Classical History, Witty Wordsmith, and Barbarian Diagrammarian.
Eclectic Ed 