Re-encoder take a folder full of files, assumes that they are encoded plain text, and saves each one into a different encoding. You specify the 'from' and 'to' encodings. If you're not sure, there's a preview function where you can experiment with different encodings until your file looks right.
The graphical version looks like this on a Mac with the encoding previewer open showing the top of a file. Click on the image to see it full size in a new browser window.
You can download Version 0.2 from Sourceforge or ponder the source code.
Re-encoder is open source software distributed under the Gnu Public License (GPL).
If you'd like to refer to the package in written work, you can use this:
Lowe W. (2012) 'Re-encoder: Switch encodings'. Java software version 0.2, URL: http://conjugateprior.org/software/reencoder/