DotCloud lets you create the best cloud stack for your application. We give developers and IT professionals the freedom and flexibility to mix and match languages, databases, caching and messaging components without the need for additional servers or infrastructure.
The free tier has room for two services; this fits nicely one Python service for Django itself + one MySQL or PostgreSQL database.
DotCloud also has support for MongoDB, Redis, Python workers (e.g. Celery), RabbitMQ, etc.; there is a paid offering, and discounted/free offerings (think "beefier free plan") for non-profits, students, open source projects.