Nick Sieger - Covers many aspects of Ruby, Rails, related topics. - http://blog.nicksieger.com/
O'Reilly Ruby - Covers many aspects of Ruby, Rails, related topics. O’Reilly Media. - http://www.oreillynet.com/ruby/
PuneRuby: Everything on Ruby/Rails - Covers Ruby and Rails, by the largest Ruby User Group (RUG) in the world, based in Pune India. - http://www.puneruby.com/blog/
One, Step, Back - Covers many aspects of Ruby: Ruse, Rake, Rails, RubyGems, RailsConf (US, Europe). - http://onestepback.org/
On Ruby - Covers many aspects of Ruby; by Pat Eyler. - http://on-ruby.blogspot.com/
Eigenclass - Repository of Ruby code, information, culture: writings, development resources, unusual idioms, hacks that bend the language, reviews and improvements of 3rd-party code, news on development: changelog summaries, translations of Japanese communications. - http://eigenclass.org/