How to change db in django depending on request.get_host()?
You might want to reconsider using a separate db for reach site. In reviewing the multi-db source, it looks like you'll run into a few scalability issues, depending on how many sites you want to support:
Currently all the databases are set up in settings.py. This could cause a few issues:

Each new site would require reloading Django. 
settings.py could get large. 

A better approach might to use a single DB and associate the site/account with each record as needed.
I am creating multisites platform. Anybody can make simple site, with my platform. I plan to use django multidb support. One db for one site. And i need to change db settings depending on request.get_host(). 
I think that i's not good idea. Prompt other decisions? How it is realised on various designers of sites?