I was poking around in this app on my iPhone and discovered this nifty feature that was released in v.2.3:
easy integration with other apps (todo apps like Todo or OmniFocus, notebook apps, etc.) – select a file in Actions mode, use Link command to copy a special URL to clipboard (iPhone OS 3.0 required) and then paste this URL link to another application that supports URL links. When you will [sic] tap this link in that other app, GoodReader will be automatically launched and the file being linked will be opened.
This feature would integrate well with Due. If you tap on an alert that includes an URL, the app will ask if you want to open that URL. So if you want to remember to review a photo you took or listen to a podcast you downloaded, this GoodReader URL scheme makes it easy to work with non-text media in your workflow while you’re on your iOS device.