Source: http://lifehacker.com/5509681/file-blender-converts-files-with-drag-and-drop-ease
Windows: File Blender is a free and portable interface for more than a half-dozen tools. Drag and drop everything from pictures to music to File Blender and convert it to something new.
File Blender is a simple GUI for the command line conversion tools included in popular applications like IrfanView and Lame MP3. Drag files into the File Blender button and convert all kinds of files including MP3s, WAVs, JPGs, and other audio and image formats.
You can download File Blender by itself or with all the support apps included. If you download the full package (4.5MB) you won't have to do any configuration at all. If you download the stand-alone interface you'll need to configure File Blender to run with your favorite command line friendly applications. Check out the site below to grab a copy or to read up on how to make your own configuration files.
File Blender is free, portable, and Windows only. Have a favorite conversion tool or trick to share? Let's here about it in the comments.