Hi Ultramarina,
I'm new to all of this but my DS6 just started using ixl at home. He's an independent reader and has been loving it. It's all drill from what I can gather but it does give you "prizes" to uncover at the end of a skill. It also tells you how many points you have (1-100) per section and my son LOVES to see how his score goes up. I paid 9.95 for a month trial but I know a lot of schools already have memberships.
Others have mentioned Dragon Box, Khan Academy (free- we may do this when our membership runs out), Mathseeds, and some others.
