Apple's app approval process is a real hurdle for anyone who wants to do rapid development of a project. I'm used to being able to deploy fixes many times in a day if need be.
- Fluid - Online editor to quickly mock up ioS or Android UIs. Safari/Chrome only.
- Gist.io: Writing for Hackers - Write a gist in Markdown, get a URL to see it nicely formatted. Just append the gist ID to the URL, e.g. http://gist.io/1397561.
- LiveCSS - Display actual colors in your stylesheets in ST2.
- Clear Eyes - Automatic retina image handling for Rails 3.1+.
- Active Record loves blocks - A reminder about some nice syntax you might have forgotten.
- What's New in RubyMine 4.5? - Quite a lot, including Sass and Slim, Sinatra, and MongoDB support.