Another neat lyrics editor is YASS, which runs on Java. What sets it appart from Composer is that it supports importing a melody from MIDI or KAR files; is you have a proper file with vocals correctly set up, there's not much more to di after importing it.
Official site: http://www.yass-along.com/
Creating a new file, by importing from .mid:
(http://i.imgur.com/6yHQk.png)
Editing lyrics:
(http://i.imgur.com/D0CSw.png)