Toodledo

While searching for a "to do" application to use with the iPod Touch I found one which synchronises with a web-based program called Toodledo. This means you can run it on the Touch and make updates as necessary - but it also means you can make changes on the web version - using a real keyboard and with a choice of lists and contexts (important if you are working David Allen's "Getting Things Done" method) and then sync these back to the Touch for offline reference.
Toodledo is available in free or paid versions, is configurable, and is simple to use. And you can just use it as a web app if that's what you want to do - and then print out your to-dos from the site.