long live Ogg Vorbis!
Ogg Vorbis offers better sound quality than mp3 while requiring only half as much storage space for comparable results and most importantly it is open and free of patents. Ogg Vorbis features a flexible tagging standard which allows complete customization of tags for a given file, including user defined tags. There are now quite a few hardware audio players that support it. By the way, you should never transcode your mp3 files to Ogg Vorbis which uses similar but different techniques to remove information and by transcoding you lose information twice. KAudioCreator (http://freshmeat.net/projects/kaudiocreator/ ) is a nice frontend to encode audio cds to Ogg Vorbis. OggEnc is part of the Vorbis tools (http://freshmeat.net/projects/vorbis-tools/). Tom (http://www.very-clever.com/)
An open, cross-platform journaling program.
A scientific plotting package.