1.ruby
http://www.ruby-doc.org/core/
代理访问:http://anonymouse.org/cgi-bin/anon-www.cgi/http://www.ruby-doc.org/core/
http://www.ruby-doc.org/stdlib/
2.rmagick
http://studio.imagemagick.org/RMagick/doc/index.html
3.gemjack.com集合的大多数rdoc(推荐!)
http://gemjack.com/