Most public libraries lend CDs and therefore accept donations of used CDs. In my experience, the library especially appreciated donations of classical and jazz music.
A library won’t value your CDs for charitable donation purposes, but ItsDeductible will provide a generic value. Thus, under the right circumstances, you can turn your unwanted CDs into a tax deduction. But even without a tax deduction, you’ll have the satisfaction of knowing that your music is widely available.
Good luck!