WHoa Helen! Here's the scoop! The Well Tempered Clavier Part I & II were written as studies for the clavier. The Prelude No.1 in C from this opus was combined by Charles Gounod with his own melody, to form "Ave Maria".

The famous "Minuet in G" is from The Anna Magdelena Notebook, which is what Bach wrote for his wife, Anna Magdelena, because she was learning the harpsichord. The "Minuet in G" was used as the tune for the 60's song "Lover's Concerto". "Unchained Melody" is by the Righteous Brothers and has a tune that is it's own, and not Bach's.

I'd have to say my favorite Bach work is Brandenburg Concerto No.3.