As a grown-up I think these Hasbro I-dogs are somewhat pointless, money-for-a-bit-of-plastic-tat that doesn't do very much and the thing I'd be least likely to choose from someone's present wish list. As a kid...I'd LOVE THEM!
Amazon have some Hasbro I-dog deals running at the moment, with various discounts on various styles.
Basically the I-dog is a robot looking dog who loves music; when you plug your MP3 player into him (or other music source) he'll start to groove away by flapping his ear, nodding his head and wagging his tail, his 'face' lights up too with different coloured LED patterns.
He's just a speaker for your electronically stored music; he doesn't download anything or store anything, he just throws some moves when you play your music through him.
See? Utterly pointless and now you know why kids are going crazy for him, or her - there are various different styles from plain black to pretty 'tattooed' versions; if I really HAD to choose one for myself, it would be the pink tattooed one and I probably wouldn't ever play music through her either.
The full I-dog retail price is £24.99 and, as I said earlier, Amazon have various discounts going on. For example, the black I-dog is just £9.99, the Dalmation I-dog is £19.99 and the pretty pink tattooed one is also £19.99.
If you really want to go crazy, there's a Hasbro i-Cy Penguin and an i-Cat too; don't even get me started on the fish version!
Thanks to Speculator and missgem at HUKD