Index: /django/db/models/fields/__init__.py
===================================================================
--- /django/db/models/fields/__init__.py	(revision 4752)
+++ /django/db/models/fields/__init__.py	(working copy)
@@ -571,6 +571,22 @@
         defaults.update(kwargs)
         return forms.DateTimeField(**defaults) 
 
+class DurationField(FloatField):
+
+    def __init__(self, *args, **kwargs):
+        super(DurationField, self).__init__(max_digits=20, decimal_places=6)
+
+    def get_internal_type(self):
+        return "FloatField"
+
+    def to_python(self, value):
+        try:
+            return datetime.timedelta(seconds=value)
+        except TypeError:
+            raise validators.ValidationError('This value must be a real number.')
+        except OverflowError:
+            raise validators.ValidationError('The maximum allowed value is %s' % datetime.timedelta.max)
+
 class EmailField(CharField):
     def __init__(self, *args, **kwargs):
         kwargs['maxlength'] = 75