I'll update the OP as people post. For more information, read through the thread to look for a personal review or post a question.
Being listed is not an endorsement by GCM. In no particular order:
Life of Fred -- goes all the way through college. Hilarious. Can be done independently.
Saxon
Dragon Box-- app and PC game. Comes in various levels from preschool through algebra and geometry.
Algebra Unplugged -- a book about algebra without any problems, it's about thinking algebraically
Calculus for Cats -- same as Algebra Unplugged
Making Friends With Numbers. by Edric Cane. I believe it's only available through LoF and CBD.
Singapore Math
Teaching Textbooks
Math U See
Mathematics Enhancement Programme
https://www.cimt.org.uk/projects/mep/index.htm
Right Start
Mister Numbers & Pattern Play Math. YouTube channel with some right-brain oriented math videos.
https://www.youtube.com/channel/UCNa...1KnF53DUmTipEw Also a website with a few feebies and things to purchase.
http://www.patternplaymath.com/
Math Lessons for a Living Education
https://www.rainbowresource.com/prod...Education/7775
Prodigy Math Game
https://www.prodigygame.com/
Big Fat Notebook for Middle School Math
https://www.amazon.com/Everything-Yo...81ST6ZH8QDVT5X
Miquon Math. Hands-on math for younger grades.
https://miquonmath.com/
RightStart Math.
https://rightstartmath.com/our-curri...r-home-school/
CTC Math. An online math curriculum that costs $118 per family and has a free trial.
https://www.ctcmath.com/how-it-works/home-school
ST Math. A challenging visual math program for k-8.
https://www.stmath.com/
Gattegno's math method, books that use Cuisenaire rods.
Crewton Ramone's House of Math
https://www.crewtonramoneshouseofmath.com/
Mortenson Math