Reading this thread made me think of parties I've been to where the Bob Dylan hardcover "Lyrics" was pulled off the shelf and we'd flip through the pages looking for singalong material ("can you play this one?").

Since the context is so informal -- not a "sing" or any such meeting of purposeful musicians and singers, but simply a gathering of old friends with shared memories -- the hit-or-miss nature of our efforts has never been an issue. Only the most familiar songs get suggested in the first place, and not all of them can be coherently played by the two or three available instrumentalists, so anything that actually gets sung is pretty well-known by the whole group and can be carried off successfully enough. (Standards aren't that high, anyway -- it's usually late in the evening.) People don't need to read every word from the book, just need a reference for which verse comes next, etc.