[Answer]-Using memcached with a dynamic django backend

You would cache whatever is being most frequently accessed from your Database. Make a list of the most frequent requests to get data from the database and cache the data in that priority.

1. Cache the most frequent requests based on category of the pictures
2. Cache based on users – power users go into cache (those which do a lot of data access)
3. Cache the most recent inserts (in case you have a page which shows the recently added posts/pictures)

I am sure you can come up with more scenarios. I am positive memcached (or any other caching) will help, even though your app is very ‘dynamic’.