public GameObject items[];

void Start()
{
GameObject[] temp = GameObject.FindGameObjectsOfType(GameObject);
for(int i = 0; i <= temp.Length; i++)
if(temp[i].GetComponent("Item"))
items[i] = temp[i];
}

void OnGUI()
{
foreach(GameObject obj in items)
if(Vector3.Distance(obj.transform.position, transform.position) < 1.0f) // Ставь свое значение
GUI.Label(new Rect (150,30,200,40), "name : "+obj.name);
}

         Cube other = gameObject.GetComponent<Cube>();     
             other.DoSomething();     
             other.someVariable = 5;

foreach(GameObject obj in cube)
{
Cube other = obj.GetComponent<Cube>();
if(other == 0)
// Ну щито поделать
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
     void Update() {
         ScriptName other;
         other = gameObject.GetComponent("ScriptName") as ScriptName;
         other.DoSomething();
         other.someVariable = 5;
     }
}

    void Update() {
         ScriptName other = gameObject.GetComponent<ScriptName>();
         other.DoSomething();
         other.someVariable = 5;
     }