At my current place of employment, we modified and extended Django Admin with the Suit[0] theme to become what was basically a CRM that drove the sales and administration of a business with >$1 million revenue.

Eventually we built an actual operations/management/sales interface because Django's admin had too much extra stuff and lacked certain things we wanted to implement, but it wasn't that difficult to put together and it worked well for several months.

[0] http://djangosuit.com/