Most widely used .wav audio compressor. The difference between MP3 and FLAC in sound quality is like night & day. If you still compress your files into MP3 for achival purposes, you should consider FLAC compression.
FLAC Frontend is a convenient way for Windows users not used to working with command lines to use the official FLAC tools. It accepts WAVE, W64, AIFF and RAW files for encoding and outputs FLAC or OGG-FLAC files. It is able to decode FLAC files, test them, fingerprint them and re-encode them. It has drag-and-drop support too. It is tested on Windows XP SP3 and Windows 7, but should work with Windows XP SP2 or newer. It requires .NET 2.0 or later.
FLAC Frontend was originally made by w.speek, but hasn't been updated since early 2003. It didn't work well in Windows Vista or later because it wasn't made with UAC in mind.
This (full) remake fixes most issues and incorporates a few new FLAC functions. The original was freeware, this remake is GPL-licensed open-source software, just like FLAC itself.