One thing we just started doing is beginner book reports. I copy a sentence from a book we read. Then he copies it in his own handwriting. This is to practice his handwriting and also at the same to study what a good sentence really looks like written by someone who is a very good writer. Then he tells me what the story was about and I write down what he said on the same piece of paper. That technique came from The Well Trained Mind. Another thing we just started doing is using The Usborne Encyclopedia of World History. I read the two-page spread to him. He picks out the important sentences. I write them down. He draws an illustration on the paper. We put it in a 3-ring binder called the history notebook. The purpose is to get a vague idea of historical stories, events, charachters, plots, and places. They'll go over all of World History again some other year.
He also has a three-ring binder for Science. I've had him write lists of our science equiptment in a chart, label parts of a flower, draw plants from my garden. For math try sumdog!
That's what I'm doing with my 5yr. old. When he was 3 he did reading eggs and Singapore early bird and Kumon Alphabet games. Now my little girl's doing those.