WaveShop is a free, open-source audio editor for Windows XP/Vista/7. WaveShop is fast, lightweight, and bit-perfect, meaning samples aren't altered unless they need to be. Editing a portion of an audio file only affects that portion; the rest of the file is untouched. Blocks of audio can be cut and pasted without changing their contents at all. This is especially useful for patching a finished master without corrupting its dither.
The program is no longer updated. Last version, 1.0.14, released in November 2013, can be still downloaded from the official website.