Creating this list for my future reference; I have not personally investigated all of these.
My Slide Rule – Searches the web for courses in any topic
Scholars Online (Classical Christian)
Elements of Mathematics: Foundations. Gifted math class for middle school.
Derek Owens (monthly subscription, Pre-Algebra through Calculus; Physics; Computer Science)
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.