django-admin-histograms
To use this app simple have your ModelAdmin subclass
django_histograms.admin.HistogramAdmin and give it a histogram_field
attribute with the name of a DateField or DateTimeField to create the
histogram over. Then you can pull up
localhost:8000/your_app/your_model/report/ to see the histogram (adjust the
URL as necessary).
The designs came from Wilson Miner's article on data visualization for A List Apart.
Using histograms in other pages
You can use the built-in histogram_for template tag:
{% load histograms %}
{% histogram_for appname.Model 'histogram_field' 1 1 %}