We have a web app that downloads a large list of simple repetitive maintenance tasks ("check amount of spare printer toner", "water the office plants", and such) with documentation, images, etc. that need to be performed regularly, and then shows the user that list so he can perform the tasks and send back the results. Some companies using this app do not allow internet access in the specific areas where tasks have to be performed, so some parts of the app have to work without it. Business requirement was "store enough info on the device to be able to run without internet access for one month".

Without an in-browser persistent database (we used WebSQL, with all the future risks), it would require some interesting workarounds (can you serialize multiple megabytes to local storage? how long will it take? will it rollback from a fault correctly?) or Phonegap type solutions.