WowMath.org is developed by high school mathematics teacher Bradley Robb. His YouTube channel has more than six hundred videos covering topics in Algebra and Calculus. You can access the videos on a mobile version of WowMath too.
The New Boston which is primarily a channel for computer science lessons also has some good playlists of geometry, algebra, and basic mathematics lessons.
Math Doctor Bob's YouTube channel offers nearly 700 video lessons on statistics, algebra I and II, calculus, geometry, and much more. The lessons feature Doctor Bob giving the lesson in front of a whiteboard so you see him and don't just hear his lessons.
Patrick JMT offers high quality math tutorials. Patrick JMT doesn't cover as many topics as Khan or Math Doctor Bob, but the videos are equally solid.
Bright Storm is an online tutoring service. On their YouTube channel Bright Storm provides hundreds of videos for Algebra I, Algebra II, Trigonometry, Precalculus, and Calculus. Bright Storm also offers some SAT and ACT prep videos.
Ten Marks is another online tutoring service that offers mathematics tutorial videos on their site as well as on their YouTube channel. Some of the lessons in their playlists include lessons on units of measurement, decimals, fractions, probability, area and perimeter, and factoring.
Math Class With Mr. V features seven playlists made by a mathematics teacher teaching lessons on basic mathematics, geometry, and algebra. In all there are more than 300 video lessons. Like most mathematics tutorials on YouTube, Math Class With Mr. V uses a whiteboard to demonstrate how to solve problems.
The Open University is one of my go-to YouTube channel for all things academic. A quick search on The Open University reveals seven playlists that include lessons in mathematics. The lessons that you will find in these playlists are more theoretical than they are "how to" lessons.
Yay Math! features an excited teacher teaching mathematics lessons to his students. The videos capture just the teacher and his whiteboard with some feedback from students. The videos cover topics in Algebra and Geometry. You can check out the Yay Math! companion website to learn more about Robert Ahdoot, the teacher featured in the videos.