OverlapSphere, check how many object with specific tag did it collide with..

This is from a script of mine, basicly just a modification of the sample script at http://docs.unity3d.com/Documentation/ScriptReference/Physics.OverlapSphere.html

     var hitColliders = Physics.OverlapSphere(transform.position, 500.00);
     var resScript : residenceData;
     var numDoors : int = 0;
     
     for (var i = 0; i < hitColliders.Length; i++) {
         Debug.Log('City sphere: '+hitColliders[i].name);
         if(hitColliders[i].tag == 'door'){
             numDoors += 1;
             Debug.Log('Door detected '+hitColliders[i].name);
         }
         
         if(hitColliders[i].tag == 'residence'){
             Debug.Log('City Detected '+hitColliders[i].name);
             resScript = hitColliders[i].GetComponent(residenceData);
             thisCity.population += resScript.population; 
         }                                        
     }
 Debug.Log('Amount of doors '+numDoors.ToString());

 

http://docs.unity3d.com/Documentation/ScriptReference/Physics.OverlapSphere.html