MiniLyrics is capable of displaying "floating lyrics", with mouse click through (or not). Works with lrc files, has a very large database (which any user can contribute to).
MusicBee can display lyrics in floating window - just choose this option from "Now Playing - Lyrics" panel.
Also, if a lrc file is stored in the same directory with the same name as the music file, lyrics will be displayed.
As for the big MiniLyrics DB, this might be useful, especially now when lrcdb.org is down.