The March 2013 release of ArcGIS Online included a new Web App Template called the Parcel Viewer. This app allows you to search for a parcel by a number of fields, select a result and show it’s location on the map with a popup. The web app template exposes a series of parameters that allow you to change the search layer, the fields to be searched, and the UI of the application. By changing these parameters, you can configure the app to search any feature service layer you include in the webmap. So we can now use this to find a hydrant, find a valve, find a customer, etc. The possibilities are endless. Here is an example of the app configured to find a hydrant.
If you want to try this out yourself, here is a blog from the Local Government team that walks you through setting up the app.