I recently traded in my Nintendo DS Lite and some old games for a (basically free) Nintendo DSi so I’ve been playing around with it a fair bit lately (especially the cameras it has). I stumbled upon a Twitter client for it called DSTwitter that is actually pretty cool:
Of course, something like the iPhone is a much better experience for Twitter apps but not everyone has one plus the DS is sometimes more convenient to quickly check up on Twitter or play a quick game while your iPhone is charging.
It’s still very much beta and it crashes a fair bit (or won’t even load any tweets) but that may have been due to other factors like a flaky wifi hotspot. It seems to be regularly updated by the developer so it can only get better with more features added.
It does require a flash cart or hacked firmware for your DS (or DSi) to use homebrew software like this but it’s worth checking out if you’re able to.