I have written about The Art of Problem Solving classes and web site in the past, but it is worth sharing about them again. It is truly a very unique web site. AOPS offers online subject classes for Prealgebra and up. Their classes are very affordable, and they are OK with a variety of ages taking their classes. The classes have a big emphasis on problem solving, and your kids come out knowing math. You can also participate in up to 3 online-class-sessions before dropping the class for a refund. AOPS continues to update and make their programs more user friendly. I find them extremely responsive to my questions and appreciate their customer service.
They also have a FREE program you can use called Alcumus. Art of Problem Solving's Alcumus offers students a customized learning experience, adjusting to student performance to deliver appropriate problems and lessons. They have a wealth of problems available for your student to solve.
The Art of Problem Solving does a nice job with gifted math students. What I also like about them is that if your child is serious about math they have a very good reputation among colleges and math minded people.
Hope this helpful.