The Justice League Unlimited episode “This Little Piggy” is iconic in that it’s the only time in the history of Batman (more or less) that we actually see Batman sing. And by “sing” I mean with passion. It’s part of the plot in case you haven’t seen the episode.
Anyway, the voice actor for Batman in that series Kevin Conroy was noted for how well he sang the song “Am I Blue?” as Batman, and as such, fans have been asking him to do a rendition of the full song for many years. Now, he’s finally done it. You can here it here.