Django admin and showing thumbnail images

This is in the source for photologue (see models.py, slightly adapted to remove irrelevant stuff):

def admin_thumbnail(self):
    return u'<img src="https://stackoverflow.com/questions/1385094/%s" />' % (self.image.url)
admin_thumbnail.short_description = 'Thumbnail'
admin_thumbnail.allow_tags = True

The list_display bit looks identical too, and I know that works. The only thing that looks suspect to me is your indentation – the two lines beginning image_img at the end of your models.py code should be level with def image_img(self):, like this:

def image_img(self):
    if self.image:
        return u'<img src="https://stackoverflow.com/questions/1385094/%s" />' % self.image.url_125x125
    else:
        return '(Sin imagen)'
image_img.short_description = 'Thumb'
image_img.allow_tags = True