I am thinking about getting my daughters their own digital cameras for Christmas. Do any of your children have digital cameras? My girls are 10 and 7 and I think they'd enjoy being able to get creative with a camera and upload their photos to their own blog.
Our 7 year old is getting one for Christmas this year. I am a HUGE picture taker (I am actually doing a wedding next month!!!!). So he has been around mommy taking photos since he was 2 days old. I was able to get a polaroid 7megapixel digital camera that was $140 for $2!!!!!!! (No, I didn't do anything illegal.......it was clearanced out at Walgreen's with a $40 rebate and I had RR to use up). So I snatched that baby up and man did it help the holiday budget!
I also got the KidTough camera for my 5 year old. She loves it. Don't take that great of a picture, but like Lolita said, its a great starter and you don't have to worry about it breaking if they drop it.
I got one for my son's 4th birthday--a preschool camera from Fisher-Price. He's 5 now and still absolutely loves it! So your older girls would be able to be much more creative. The photos on the "kid" camera are terrible, and in a couple years he'll get a "real" camera. (He's pretty good with my Nikon SLR, but I don't really want him carrying it, so he can't really be free to snap whatever he wants.)
Plus--selfish--I love having a record of the world through his eyes.