I found a scrapbook activity online, making a scrapbook out of brown paper lunch sacks. There's links on the left of the page for making books out of toilet paper rolls too. Fun, new, hands-on. Doesn't matter if it looks sloppy. I just started making one for Father's Day. But she could make a book of poems, a book of her art, a book of her family album.
I like the idea of a big jig-saw puzzle. Let her pick one out at the store and pick a spot to do it in. Spend a few mins every day so the puzzle will take a long time. Or the dollar store has smaller puzzles.
How old is your son? Maybe she can teach him, read to him, make him a scrapbook.
Let her earn an allowance from you helping you change diapers, sweep the floor, unpack the dishwasher.....
get her on websites. www.pbskids.org has games. Curious George has a LOT of games.
Keep with the cooking. Let her find recipes online (put her on a kids website like http://www.childrensrecipes.com/). She can help make lunch. This will help with reading skills and math skills too (double a recipe, have her do 1/3 a cup. Let her play with the measuring cups. See if 3 1/3 cups really equal one cup.)
That being said, do fun math games. Use rice or beans to measure things. Learn on her own about cups/pints/quarts/gallons. Get old sour cream containers, ice cream pints, etc. Wash them and use those to help her learn what a pint is, a cup is, etc. (Sorry - I'm a former teacher. It's in my brain to do this sort of thing. My 2nd graders liked learning with these items they had at home - the ice cream containers and such).
Play in the sprinkler! Get squirt guns and water balloons.
Go for a walk around the neighborhood and play "I spy" at the same time, or have her collect things along the way. When she gets home, let her make a picture book for your son (with the brown paper sacks). Tape the item to the book and write what it is on each page. ie: ROCK with a small rock taped to it. FLOWER with a dandlion taped to it. GRASS with lots of grass taped to the book.
Cut out pictures from magazines and make a collage. (animal collage, my favorite things collage, etc)
Or cut out the pictures, glue them to cardstock (old cereal boxes), tape those to a popsicle stick, and have yourself a litle puppet show. She can write a script!
Good luck. I have a book called "365 tv free activities" with tons more ideas. See if you can get a book like that for more ideas.