Ask HN: If you only had 40 hours to learn a new IT based skill what would it be?

Python. IMO, it's so well designed that you can gain a comfortable (albeit still beginner) grasp on it within 40 hours, especially if you have prior programming experience.

How to build a lean startup with Steve Blank https://www.udacity.com/course/ep245

There are many many IT skills you could learn in 40 hours. Assuming you are not a complete n00b, how about learning Ruby and Sinatra (a "framework" for rapidly creating web applications). You could easily make it through the book, "Jump Start Sinatra," in less than 40 hours, for example.

Is this the type of response you're looking for? If not, please clarify. Good luck!

Metrics measurement and tracking of some sort, depending on your area of interest and existing expertise. That could be Graphite and statsd, or a particular type of web analytics like Google Analytics or MixPanel. It takes roughly 40 hours to get a good basic understanding, implement, test, and start tracking useful things with each of those.

I'd go with NoSQL (any of them, overview of all of them?) or AWS/cloud stuff, because I'm already familiar with Linux administration and RoR. In the enterprise you don't get to work with that sort of technology, so that's where I'd spend my time.

Web security and attack vectors, seriously. Will be helpful regardless of the technology you'll choose to build web apps.

what current skills do you have? I would pick a skill to compliment my current skills.

Both Angular and Ember so I can at last make my own mind up on which is better!

Linux servers administration.

Mh or ruby and rails (but 40h are not enough for both) or probably GO

Either Python or Ruby. Photoshop is also a good choice.

Graphic design.

State-of-the-art security and crypto.

I'd learn Chef or Puppet.

AI (in games, mostly)

node or basic sysadmin or django

java script, node.js or PHP