Ruby on Rails - The 10 Most Marketable Web Development Skills

After the brief talk on Ruby on Rails at Twincling society which was successful and satisfactory, I am keen on writing and talking more on Ruby on Rails development.
So one of the FAQ's I face most is
What is Ruby on Rails and what is the market for it?
I stumbled across one such article "The 10 Most Marketable Web Development Skills", where the list of web development skills provided.

Note:

• This is not any comparison but just listing out current web developement skills that have market.

• The order of the list is not based on any popularity.