I have a syntax highlighting pattern for ruby for nedit. It isn't
perfect (and screws up occasionally) , but it is OK and much better
than nothing. Please feel free to improve let me know of any bug
removal please).

This should be inserted into your .nedit file with the syntax
highlighting patterns for other languages (mostly set to default in my
..nedit file

============================================
Ruby:1:0{\n\
		Keyword:"<def>|<end>|<do>|<if>|<else>|<elsif>|<unless>|<until>|<begin>|<while>|<ensure>|<rescue>|<alias>|<for>|<in>|<super>|<self>|<return>|<case>|<when>|<and>|<or>|<not>|<defined\\?>|<next>|<redo>|<retry>|<then>|<yield>|<break>":::Keyword::\n\
		Comment:"#":"$"::Comment::\n\
		Rubydoc:"=begin":"=end"::Preprocessor::\n\
		String1:"""":"""":"\\n":String::\n\
		String2:"'":"'":"\\n":String::\n\
		Shell Command:"`":"`":"\\n":Plain::\n\
		class variable:"@+[A-Za-z0-9\\?_]+":::Label::\n\
		class name:"<class>|<module>":"$":"\\n":Label::\n\
		block1:"\\{":"\\}"::Plain::\n\
		block2:"do	":"end"::Plain::\n\
		block3:"begin	":"end"::Plain::\n\
		constant2:"[A-Z][a-z0-9\\?_]*":::Character Const::\n\
		preprocessor:"^<require>|<load>|<BEGIN>|<END>":"$":"\\n":Preprocessor1::\n\
		constant:"<nil>|<true>|<false>":::Character Const::\n\
	}
============================================ 


Hope this helps

Steve