KarASS (Karaoke to ASS, or Karaoke ASSistant, also カラス or КАРАСЬ) is a tiny tool I've made to easily create timed lyrics for my DJ sets.

You can time kanji lines with furigana, slow down and speed up the song for more precise timing, and do all that without having to put your hands away from the keyboard.

Song used for this test: Acid Stone Valley feat. YURiE — Sora ni Saku
(No copyright infringement intended, it's just a relatively easy paced song I've had on my to do list)