JSON Viewer
http://jsonviewer.stack.hu/ is an awesome tool, especially for Ruby Noobies. Basically you can take any nested element and this site automatically formats it in an easily readable way. So any array that contains other arrays, any JSON object, etc. This tool has been priceless (literally because it is free) in my learning and fault finding. I have used it so much that I am starting to just be able to read the raw object code now but when I come against a complex XML structure of any kind the first thing I do is throw it inot this page.
Code Sharing
CodeShare.io is realtime code sharing for developers via the browser. You simply share the same URL and can see the same code / text much like you can via Google Docs. It might be useful if you are condicting an interview by phone for example.