I have been using DesktopLyrics from day 1 and can certainly recommend it. I perform shows singing with accompaniment on my MacBook. I display iTunes smart playlist on one side with DesktopLyrics on the other. I read the lyrics while I sing, unless I have memorized them. Although the auto page turning works well, I do not have the confidence to use it and prefer to have all the lyrics on one page. Therefore I do spend a lot of time shaping my lyrics pages, with different size fonts and the tools allow me to do so. I depend entirely on DesktopLyrics for my shows, and would be lost without it. If I could suggest one feature, it would be to be able to have a tool that says something like "Display all lyrics on one page". This feature may be present, but I might not have figured out how to do it, without much editing.
One comment on finding lyrics (on a Mac anyway). Just do a search such as 'lyrics It's a wonderful world', and choose from any of the number of sites that has the lyrics. For a specific version, try search 'lyrics It's a wonderful world louis armstrong'.
A great app. Thanks Julian.