I have a table with an IntegerField (hit_count), and when a page is visited (for example, http://site/page/3) I want record ID 3\'s
If you use Django 1.1+, just use F expressions:
from django.db.models import F
...
MyModel.objects.filter(id=...).update(hit_count=F('hit_count')+1)
This will perform a single atomic database query.
As gerdemb says, you should consider putting this in a middleware to make it easily reusable so it doesn't clutter up all your views.