This is cool:
http://tekutekuangel.jp/index.html
A Tamogotchi with built in pedometer, called Teku Teku Angel. The only way to improve the form of your Gel-kun is to walk, smart idea. I think they date back to the original Tamogotchi fad.
Now, though, there is a box set with DS cart called Teku Teku Nikki (diary?), which can communicate with the Gel-kun to give you stats. This is based on the steps recorded, and includes how far you would have walked across Japan 
There is a guide to starting off with a Teku Teku Angel here:
That's inspired. What a genius way to get kids moving. We badly need something like that over here, only my fingers are so fat now I doubt I could operate a tamagochi
Those electronic little pets have those all ready with steps tracked. Nintendo did one too the Pikachu thing had electricity generated by walking I think.
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"And I'm Barry Hercules, Doc"
Yeah thats right, there seems to be a whole sub-genre of them.
I like the DS diary link up idea, that would be really good fun (if you could suss it out).
I don't remember the pedometer Tamogotchis coming out in the west though.