Despite all the computers, cloud servers and devices that are 'almost computers' and similar I have access to I still hadn't found a good answer to this type of problem:
I have some time spare, I want to be able develop and poke around with Drupal 8 whenever and wherever.
Of course you could substitute 'Drupal 8' with many other things in the above problem.
Perhaps I get somewhere 20mins early I can grab a coffee, whip out a Chromebook and continue where I left off, perhaps fire up a web browser on a computer somewhere I am contracting, perhaps I want to teach or show somebody something quickly without the overhead of first going through setting up a development environment.
Virtual machines, and the convenience of Vagrant solve the problem to some extent and are a great choice in many cases, but you still need to bring some fairly heavyweight resourses with you and plan ahead, some devices you may not be able to run a virtual machine on.
Enter Codio WEB IDE
I tried installing a PHP cms called SilverStripe into a Codio project and it worked, after trying a few more things in different projects I thought I would have a go with Drupal 8, I didn't expect it to work. Drupal 8 is a large beast and not even production ready yet, even so within a short space of time I had a working Drupal 8 project.
When you are working on your project in the web ide you can access a command line to your box where you can do most things that you would on a normal server, you also have access to a Box Url where you can view the server output of your project in another browser tab.
With full Git support and the ability to add tools like Composer and Drush the Codio project is a place where I can actually develop and experiment with Drupal 8 at the drop of a hat, from lots of different places.
You can start doing all of the above for free.
Codio is still in Beta, I use it regularly and although I rarely have problems occasionally there have been performance or technical issues, usually they are quickly resolved.
I suspect the Box server may struggle a little with a large number of modules enabled or under any other test conditions of high load, I did find problems with running tests in the UI (they ran fine through Drush though).
With a free account your projects are public, although working on public code for an opensource project that is hardly a problem. A paid account costs just $8pm though (plus local taxes), I am more than happy to pay that for the use I get out of Codio.
The web ide is very good but can't offer some of the functionality you may find in Netbeans or PHPstorm (functionality that requires analysis of the entire code-base).
An easy starting point
I have written an article about how to set up a Codio project for Drupal 8 development and also a little script on Github that will set up everything for you, please feedback if the script doesn't work for you, the aim is to allow automatic setup and install of the latest Drupal 8 code into and an empty Codio project. I try to steer away from putting anything too technical into blog posts as blog posts age naturally but technical articles and things on Github are easier to keep updated.
Codio has a terrific educational potential it is easy to setup widely accessible working examples and public projects can be forked. I have just started using it to aid helping somebody learn to code, Codio provides a great bridge between quickly getting started but still keeping in touch with servers, software and command-line.