Already have it (Score 1)

Colleges have been doing this for a few years now in the dorms. LaundryView and eSuds are the two big players in the market... you can look online to see if there are washers/dryers available so you don't lug all of your stuff downstairs only to find it completely full, and it'll notify you when your things are done. You can also sign up for alerts to let you know when machines do open up if they are all in use.