Aaron Patterson
Also known as @tenderlove, Aaron did change the parsers arena in the Ruby world with his contributions to open-source projects such as Psych, the new Ruby 1.9 YAML parser. Moreover, if you deal with XML nowadays, you’re probably using Nokogiri underneath. Before that, we only had REXML and Hpricot, but Nokogiri delivered on performance. Another project was Mechanize. Because of that, we now have great parsers for the main internet formats, especially if you consider that in Rails, the JSON parser is the YAML parser.
Gregory Brown
Also known as @seacreature and also known for Ruby Mendicant. I was used to using his Ruport project before, which leverages the ancient PDF Writer to generate PDF reports. But PDF Writer was abandoned. So Gregory decided to create a new foundation to deal with PDF, and from there, we got Prawn, a more modern and capable Ruby library. Besides that, he authored the “Ruby Best Practices” book, which I recommend to anyone interested in improving their skills with Ruby.
Nick Quaranto
Also known as @qrush, he is young and works for Thoughtbot, the company that brought many great open-source projects such as Paperclip or Shoulda. But Nick had a complaint: publishing gems through the good old RubyForge.net was a tedious process.
Github radically changed the working process with open source, but we still had to cope with the old way of publishing the gem packages. So Nick created Gemcutter.org, which evolved rapidly and ended up replacing Rubygems.org, becoming the de facto gem repository. So, GitHub + Gemcutter modernized our open-source process.
Wayne E. Seguin
This is easy: @wayneeseguin. Wayne became well known for his most recent project, the RVM. It is now possible to have many different versions and different Ruby implementations running in the same environment. We can have Ruby 1.8 and 1.9 and JRuby running along. Even better, we can configure each project with its own particular Ruby implementation. A simple “rvm ruby-1.9.2” command is enough to hot-swap environments. This changed how our projects were organized, making it an order of magnitude easier. Moreover, it made it easy to have multiple web apps that depend on different Ruby settings running side by side on the same web server. Literally worth the award.