The ArcGIS Online map allows for filtering layers but not a way to search for features within a layer. Currently, the only application template of which I am aware that allows searching for features in a map layer is the Parcel viewer. It allows searching of one layer by multiple fields, but the results only show the content of the field of the match. For example, a search can be set for a NAME field and an ACTIVITY field (with a list of activities). The results shown after searching for a site by the activity field is the list of activites. Ideally, it would show the name or the park. If 8 sites match a search for "camping" the result is 8 instances of "camping" instead of Abe Park, Jack's Park, etc. It would also be useful to search for features in more than 1 map layer....search for county, search for property, etc.