You could spend a lot of time exploring the whole site (and I recommend that you do), but I'll point you in the direction of a few of my favorites...
I'd head to the investigate page first, as it'll take you to lists of inquiry activities you can do with your students.
I've spent the most time in the Countertop Chemistry section, in fact, that's how I first came across The Science House. I have found this Commercial Equivalent of Chemicals to be handy.
Spend some time exploring and see what you can bring to your classroom!
