I’m always forgetting the handy Ruby tab triggers for TextMate. Today I went through them and highlighted a few that you just can’t afford to miss.
r # => attr_reader :attr_names
w # => attr_writer :attr_names
rw # => attr_accessor :attr_names
req # => require ""
mm # => def method_missing(meth, *args, &block); end
am # => alias_method :new_name, :old_name
: # => :key => "value",
doo # => do |object| end
ea # => each { |e| }
patfh # => File.join(File.dirname(__FILE__), *%w[rel path here])
In a related note, I recently purchased the TextMate beta book from Pragmatic. Full of useful tidbits and highly recommended.

