I just uploaded a minor update to Convert to FLAC. It adds support for converting Windows Media Audio (WMA) Lossless and Meridian Lossless Packing (MLP). MLP is a format commonly used on DVD-Audio and Blu-ray audio discs; note that you'll need some way to decrypt and rip the MLP files from the disc - they can't be copied directly.
For more information:
Convert to FLAC home page and downloads
Convert to FLAC ChangeLog