Here are some Ruby and Rails things that have caught my attention. In the interest of sharing and documentation, in no particular order:
Pry is a powerful alternative to the standard IRB shell for Ruby. I learned about it at CodeSchool, on one of the Code-TV videos. Pry provides source code and documentation browsing, the ability to live edit defined methods, syntax highlighting, command shell integration and other things of goodness.
Also recommended is the CodeSchool Code-TV episode on Guard and Spork, which look like a great 1-2 punch for driving TDD.
From a recent Ruby MeetUp at the Punchbowl place in Framingham (thanks for the hospitality, pizza and beer!), I picked up these two tidbits:
RubyFiddle is a website that lets you try out Ruby code in the browser and save snippets as gists. It lines up nicely with my personal philosophy that to be a great ROR engineer, one needs to be a great Ruby engineer. RubyFiddle has easily selectable key bindings for none, vim or emacs, which I find rather considerate and helpful.
I also learned about the Null Object Pattern, which has some compelling features and deserves to be in the toolbox of the enlightened engineer.