Toast created in an IntentService never goes away

The problem is that IntentService is not running on the main application thread. you need to obtain a Handler for the main thread (in onCreate()) and post the Toast to it as a Runnable.

the following code should do the trick:

@Override
public void onCreate() {
    super.onCreate();
    mHandler = new Handler();
}

@Override
protected void onHandleIntent(Intent intent) {
    mHandler.post(new Runnable() {            
        @Override
        public void run() {
            Toast.makeText(MyIntentService.this, "Hello Toast!", Toast.LENGTH_LONG).show();                
        }
    });
}