Here are a few exciting links I just discovered, I particularly like the fact that they are printable and from what I saw so far they sound very promising.
Engineering lessons for 8-18 year olds, how amazing is that?
An Art Appreciation and Social Studies curriculum for Elementary age children, from what I looked at so far I really liked it, but of course you have to pick and choose with some of the things.
Meet the Masters Curriculum
The What Your Grader Needs to Know series are available for download from Coreknowledge.org . I wouldn't necessarily use it as a textbook but it is useful to give you ideas of subjects and concepts to explore with different ages.
I also saw some interesting ideas for teaching art, writing, poetry, etc through weekly or monthly challenges/assignments that a few people can do as a group. Each person does the assignment and then the work is displayed, discussed, etc. The idea being that it gets you into the habit of doing something on a regular basis, such as writing, drawing, reading, you name it. You don't have to participate in any existing group and you can certainly make your own. Food for thought.