Ruby:

• http://blog.endpoint.com/
• http://iwanttolearnruby.com/
• http://blog.rubybestpractices.com/
• http://blog.headius.com/
• amesgolick.com
• http://tech.pro/tutorial/1226/basic-rubygem-development

Particular topics:

• http://www.dreamincode.net/forums/topic/166151-threading/ - Threads

Other:

• http://www.igvita.com/

Podcasty:

• http://ruby5.envylabs.com/

Ciekawe stack overflowy:

• http://stackoverflow.com/questions/4113299/ruby-on-rails-server-options/4113570#4113570
• http://stackoverflow.com/questions/917566/ruby-share-logger-instance-among-module-classes
• http://stackoverflow.com/questions/1681745/share-global-logger-among-module-classes?rq=1
• http://stackoverflow.com/questions/746207/ruby-design-pattern-how-to-make-an-extensible-factory-class