This year we are doing the Chronicles of Narnia Literature-based Unit Study. It is called Further Up and Further In. While it is a Christian based curriculum, we don't actually do the bible activities very often. I have my own unique beliefs about that but it is a GREAT literature, vocabulary, science and more curriculum. Technically, the only things you NEED to provide are math and spelling, but I feel it is weak in the English/grammar department. (That's what happens when you are an English major and writer I suppose.)
Exercises in English: I supplement with this because the girls like it, it's a well rounded grammar book and it is in depth enough for me to work with.
For science we really do a large variety of things, same with geography and social studies. There isn't a set curriculum there, just as we go. For example, we learned all about Ireland around St. Patrick's Day and are currently doing a beaver unit in science. I love homeschoolshare.com for that.
For Math we are doing Moving with Math. I just started it because the haphazard math wasn't working and I hated K12's math. I LOVE this manipulatives based approach and especially like the teacher's guide to be honest. AND that I don't have to buy anything else for future kids since it's reproducible.
We did an online school earlier in the year so we still do spelling, French and Latin through K12. I am also using a variety of resources for state history.