Monkey's Audio
Lossless compression is something that seems like it should be an oxymoron. After all, when an uncompressed audio file is compressed to a format like MP3, some of the dynamic range of the music disappears. Lossless compression really amounts to applying better mathematical algorithms in shrinking the file size, rather than eliminating information in the process of making the file size smaller. I've been a FLAC fan for a long time, particularly because of it's solid cross-platform support. Lately, I've been using Monkey's Audio to archive giant sized audio files because I can shrink files to an even smaller size without any quality loss, which is quite useful for archiving backup copies of things like the weekly radio show, or uncompressed versions of live recordings. A few plugins support playback of APE files directly in players like JetAudio and WinAmp, but I'm more inclined to use the format strictly for archiving my audio at the smallest sizes possible without losing any quality in the process. Using Monkey's Audio Compression, I can usually store at least two album's worth of material on one CD-R, or around 12 album's worth of tracks on a burned DVD without the quality loss of a compressed format. Even if you plan on storing all your uncompressed music on a network drive, APE files make a good method for getting double the amount of file capacity, without the quality hit of lossy audio formats.