Index: django/conf/__init__.py
===================================================================
--- django/conf/__init__.py	(revision 11620)
+++ django/conf/__init__.py	(working copy)
@@ -85,6 +85,17 @@
                     setting_value = (setting_value,) # In case the user forgot the comma.
                 setattr(self, setting, setting_value)
 
+        if hasattr(self, 'BOOTSTRAP_CALLBACKS'):
+            try:
+                callbacks = self.BOOTSTRAP_CALLBACKS
+                for callback in callbacks:
+                    try:
+                        callback()
+                    except Exception:
+                        raise # TODO handle error in callback
+            except TypeError:
+                raise # TODO handle non-iterable
+
         # Expand entries in INSTALLED_APPS like "django.contrib.*" to a list
         # of all those apps.
         new_installed_apps = []
Index: django/db/models/loading.py
===================================================================
--- django/db/models/loading.py	(revision 11620)
+++ django/db/models/loading.py	(working copy)
@@ -52,6 +52,12 @@
         try:
             if self.loaded:
                 return
+
+            if hasattr(settings, 'PRE_MODEL_CALLBACKS'):
+                callbacks = settings.PRE_MODEL_CALLBACKS
+                for callback in callbacks:
+                    callback()
+
             for app_name in settings.INSTALLED_APPS:
                 if app_name in self.handled:
                     continue