Index: django/test/simple.py
===================================================================
--- django/test/simple.py	(revision 13409)
+++ django/test/simple.py	(working copy)
@@ -244,8 +244,10 @@
                     app = get_app(label)
                     suite.addTest(build_suite(app))
         else:
-            for app in get_apps():
-                suite.addTest(build_suite(app))
+            for app_name in settings.INSTALLED_APPS:
+                if app_name not in settings.TEST_SKIP_APP_TESTS:
+                    app = get_app(app_name.split('.')[-1])
+                    suite.addTest(build_suite(app))
 
         if extra_tests:
             for test in extra_tests:
Index: django/conf/global_settings.py
===================================================================
--- django/conf/global_settings.py	(revision 13409)
+++ django/conf/global_settings.py	(working copy)
@@ -515,6 +515,9 @@
 TEST_DATABASE_CHARSET = None
 TEST_DATABASE_COLLATION = None
 
+# A list of INSTALLED_APPs that should (by default) be skipped when running the tests.
+TEST_SKIP_APP_TESTS = ()
+
 ############
 # FIXTURES #
 ############
Index: tests/regressiontests/skip_these_tests/__init__.py
===================================================================
Index: tests/regressiontests/skip_these_tests/tests.py
===================================================================
--- tests/regressiontests/skip_these_tests/tests.py	(revision 0)
+++ tests/regressiontests/skip_these_tests/tests.py	(revision 0)
@@ -0,0 +1,17 @@
+"""
+These are tests that should never run as they are included in the TEST_SKIP_APP_TESTS
+"""
+
+from django.test import TestCase
+
+class SkipTheseTests(TestCase):
+
+    def test_this_test_should_be_skipped(self):
+        """
+        This test should never run as the app is registered in TEST_SKIP_APP_TESTS
+        """
+        self.fail(
+            "This test should never run as the app (modeltests.skip_these_tests) "\
+            "is registered in TEST_SKIP_APP_TESTS"
+        )
+
Index: tests/regressiontests/skip_these_tests/models.py
===================================================================
Index: tests/runtests.py
===================================================================
--- tests/runtests.py	(revision 13409)
+++ tests/runtests.py	(working copy)
@@ -88,6 +88,7 @@
     from django.conf import settings
 
     old_installed_apps = settings.INSTALLED_APPS
+    old_skip_app_tests = settings.TEST_SKIP_APP_TESTS
     old_root_urlconf = getattr(settings, "ROOT_URLCONF", "")
     old_template_dirs = settings.TEMPLATE_DIRS
     old_use_i18n = settings.USE_I18N
@@ -97,6 +98,7 @@
 
     # Redirect some settings for the duration of these tests.
     settings.INSTALLED_APPS = ALWAYS_INSTALLED_APPS
+    settings.TEST_SKIP_APP_TESTS = ('regressiontests.skip_these_tests',)
     settings.ROOT_URLCONF = 'urls'
     settings.TEMPLATE_DIRS = (os.path.join(os.path.dirname(__file__), TEST_TEMPLATE_DIR),)
     settings.USE_I18N = True
@@ -176,6 +178,7 @@
 
     # Restore the old settings.
     settings.INSTALLED_APPS = old_installed_apps
+    settings.TEST_SKIP_APP_TESTS = old_skip_app_tests
     settings.ROOT_URLCONF = old_root_urlconf
     settings.TEMPLATE_DIRS = old_template_dirs
     settings.USE_I18N = old_use_i18n
Index: docs/ref/settings.txt
===================================================================
--- docs/ref/settings.txt	(revision 13409)
+++ docs/ref/settings.txt	(working copy)
@@ -387,7 +387,19 @@
 
 See :ref:`topics-testing`.
 
+TEST_SKIP_APP_TESTS
+~~~~~~~~~
 
+Default: ``()`` (Empty tuple)
+
+A tuple of strings designating all applications that should be skipped
+when running tests.  Each string should be a full Python path to a Python
+package that contains a Django application.  Use this setting to exclude
+any thirdparty applications that are listed in :setting:`INSTALLED_APPS`
+that should not be tested as part of your normal workflow.  Note that
+if you specify a set of applications as command line arguments to the test
+command, they will not be excluded even if they are listed here.
+
 .. setting:: DATABASE_ROUTERS
 
 DATABASE_ROUTERS