Is she already reading? If not, there is a program called "Sing, Spell, Read and Write" that is a lot of fun and has rewards for each lesson finished. I home school and started both of my boys with this. They learn grammar through songs and little games. A little race car keeps track of where they are in the "race for the finish line". The program comes with music CDs to sing along with, and phonics books, cut and paste, everything you need from K-3rd grade. You can check it out online.
If you are interested in a Christian world view, try Alpha Omega Publishers. I think it is AOP.com. You can get her started at whatever grade level you want and can choose to either buy the full curriculum, just one subject, or different subjects at different levels.
Another good one for math is "Making Math Meaningful" which not only teaches how to do math, but really stresses why math works. If they can understand why 2+2=4 they will be able to do better later when having to analyze problems rather than just memorizing facts.
Good luck. And more than anything, have fun!