One of my recommended books for homeschooling is Doing the Days by Lorraine Dahlstrom -it has been quite a hit in our household! The book contains "A years worth of Creative Journaling, Drawing, Listening, Reading, Thinking, Arts and Crafts activities for Children ages 8-12". I bought it because we do quite a lot of journaling and I thought it would be a great way to motivate the children.
The book contains at least two entries for each day of the year, each followed by an idea for writing, drawing or further investigation. Some of the entries are very dry (although I went off to find an example of this and couldn't - oh!, how about "Today is International Literacy Day. Literacy means the ability to read and write. More than 25 perent of adults in the world do not know how to read and write - write about why you think its important to read").
We don't use it every day (so hopefully it will last us a few years) and we don't generally do the prescribed activity. But it has sparked lots of discussion and further investigation. For example, September 4 has this entry: "On this date in 1886, Geronimo, an Apache Indian surrendered to the US Army at Skeleton Canyon in the Arizona Territory. Geronimo and his followers agreed to live on a reservation in Florida (etc.)". But this of course begs the question - if Geronimo is an apache indian - why do we shout his name when we jump? (The answer is here). And we spent an entire morning designing skyskrapers after reading of Louis Henry Sullivan (who is credited with 'inventing' the skyscraper). So whilst we don't use the book as intended - we have had fun homeschooling with it.
The book is quite hard to get hold of but Lorraine also does another (more readily available) book called Writing Down the Days: The Young Person's Guide to Becoming a Writer: 365 Creative Journaling Ideas for Young People which I believe is similar but has only one writing activity per day.
I have also heard quite good things about The Creative Journal for Children. I haven't seen it myself yet, but I will try to review it soon.
I also have an article on Journaling with children you may be interested in.