Pretty much what the title says. The ones that turn up through casual google searches are infested with dodgy or downright malicious javascript, borderline (or further) non-work-safe banner ads, not to mention sometimes bafflingly inaccurate lyrics.
Here is what I have under lyrics in my Bookmarks menu. The quality varies greatly from site to site.
http://www.allthelyrics.com/index/
http://www.sing365.com/artist/a.html
http://directory.google.com/Top/Arts/Music/Lyrics/
http://www.theguitarguy.com/songs.htm
http://www.clinton.net/~sammy/lyric.htm
http://www.songtitle.info/
http://www.music-sites.net/?action=mediasearch&src=lyrics
http://lyricserver.com/
http://www.songfile.com/
http://www.songmeanings.net/index.php
http://www.getlyrical.com/
http://www.geocities.com/tvshowthemelyrics/index.html
http://gunther.simplenet.com/v/toc.htm
For general rock and pop music lyrics, go to www.azlyrics.com. If you like hard rock and heavy metal, visit www.darklyrics.com .