One of the ATC people might know better, but there are a number of systems used to handle ATIS broadcasts and I am not sure all of them are transcribed for digital dissemination via FMS or other means, except at the very largest airports. Metars are already provided as you know. Another thing to think about, particularly if you are using the data for flight planning purposes and want the proper legal foundation for using it, is a transcription service needs to be FAA approved using the "QICP" system (Qualified Internet Communications Provider). This can be seen on Aviationweather.gov and some others like DUATS and FlightPlan.com, but they are not the full ATIS broadcasts containing local airport info you would seem to require.