Sound Editors (FREEWARE)

Audacity - The open source sound editor (1.2.6 Review!)
Features:

• Cross-Platform
• Record live audio
• Edit Ogg Vorbis, MP3, WAV or AIFF sound files
• Change the speed or pitch of a recording
• Remove static, hiss, hum, or other constant background noises
• Many more!

Wavosaur - Audio editor with VST support
Features:

• Multiple Document Interface for working with many files in one session
• ASIO support
• Edit Ogg Vorbis, MP3, WAV or AIFF sound files
• Change the speed or pitch of a recording
• Export files as text for using in software such as Matlab, Excel or PSpice
• Frequency analysis : 2D spectrum & 3D spectrum, sonogram

mp3DirectCut - All you need to cut your mp3
Features:

• Non-destructive cut, copy, paste
• Fast mp3 visualisation and easy navigation
• High speed recorder · Command line usage
• Supports Layer 2 (dvd/dvb audio)
• Remove static, hiss, hum, or other constant background noises
• Volume change, fade, normalize, pause detection