Store word frequency.
When a user imports a text, store for each word how many times it appears in texts.
Don't know yet if I will implement this feature or not, it would slow down importing texts. It may be something that would fit better after linguacafe has a job queue, and it can be done in the background.
I was just thinking about a feature like this. With the new queue system it should be pretty seamless to implement in the background I would think. If it's really resource hungry, it might also make sense to make it on-demand. That way it wouldn't have to be done on import and the user could just click a button to get frequency stuff per chapter/page or book if/when they want it.
It terms of frontend, do you think it would make sense to include in the vocabulary menu. Per-chapter and global? Or, should it have a separate set of screens?