This is a Rails application demo that was described in this article.
It shows how to combine all these things together to make a financial planning web application in a moment:
The application is deployed on Heroku.
It demonstrates how heavy calculations can be defined on DB level instead of application one. That makes application faster and robuster.
Look at the "virtual model" CumulativeProfit here.
This model uses cumulative_profits view as a source feed.
The model has all reading facilities like a "traditional" model, expect it can't write data.