K5 Learning has an online reading and math program for kindergarten to grade 5 students. I've been given a 6 week free trial to test and write a review of their program. If you are a blogger, you may want to check out their open invitation to write an online learning review of their program.
I already took a quick peek at some of their demos and it looks pretty interesting. I'm going to take the next 6 weeks to check it out and get some feedback from a friend's child to get a student perspective as well! I'll be back in about 3 weeks to let you know what we think!