Great program for backing up your CD's. You can also convert or rip to MP3, OGG, AAC, and others.
http://cdexos.sourceforge.net/

FLAC stands for Free Lossless Audio Codec. It is a general purpose lossless audio format supported by many programs.
http://flac.sourceforge.net/

From their site:

foobar2000 is an advanced freeware audio player for the Windows platform. Some of the basic features include full
unicode support, ReplayGain support and native support for several popular audio formats.

I've been using it for years, now. Before this, I tried !WinAmp, Sonique and others in the past, but they all turned buggy or into bloatware.
http://www.foobar2000.org/

Still my favorite video player and works for most formats.
http://www.videolan.org/

Apparently this is not as supported as it used to be, but some others have picked up where he left off.
http://www.afterdawn.com/software/video_software/video_players/media_player_classic.cfm/v6_4_9_1/20080127
http://forum.doom9.org/showthread.php?t''128616

Here is the link to the unpatched original version:
http://sourceforge.net/projects/guliverkli/

Audacity is for recording and editing sounds, able to save in many formats.
http://audacity.sourceforge.net/