Why limit to 48 hour rails contest?
I am trying a new tradition called "weekend blitz". The idea is that I create a new rails app every weekend or so to expand and develop my rails chop as well make me a deployment and monitoring master.
The hope is that most of the rails project will pay itself off in by 0.03 cents in revenue each day, and some will pay big from the start.
Nearing the end of the year domain hosting for each of the project, I either decide to cull them by selling or keeping them and develop it further. Eventually, it will narrow itself more and more to profitable enterprises.