What I like about the DS is, that you not only can play games with it, but that also applications are released. Last week there was an ebook-collection released for the DS, and some weeks ago the Korg DS-10 synthesizer. People are beginning to get creative with that.
Absolutely low-tech hacking
This guy here shows us how to turn the DSi with the Korg DS-10 into a talkbox, simply by using a straw. It is recommended to try this out on the DSi, because the speakers on the DSi are “hidden” just under one big hole, compared to the DS lite, where the speakers are below a “matrix of hole”, that are much more difficult to focus the sound with the straw. Once fixed, voila, you have a nice little, portable talkbox. I am sure that this can also get more convenient, than holding the DS close to your mouth all the time. There are rumours, that an Korg-engineer itself (Mr.Kanamori-san) came up with the idea.