GameObject.FindGameObjectsWithTag  

// Instantiates respawnPrefab at the location
// of all game objects tagged "Respawn".
var respawnPrefab : GameObject;
var respawns = GameObject.FindGameObjectsWithTag ("Respawn");
for (var respawn in respawns)
Instantiate (respawnPrefab, respawn.position, respawn.rotation);
// Print the name of the closest enemy
print(FindClosestEnemy().name);

// Find the name of the closest enemy
function FindClosestEnemy () : GameObject {
// Find all game objects with tag Enemy
var gos : GameObject[];
gos = GameObject.FindGameObjectsWithTag("Enemy");
var closest : GameObject;
var distance = Mathf.Infinity;
var position = transform.position;
// Iterate through them and find the closest one
for (var go : GameObject in gos) {
var diff = (go.transform.position - position);
var curDistance = diff.sqrMagnitude;
if (curDistance < distance) {
closest = go;
distance = curDistance;
}
}
return closest;
}