Free Audio Editing Tools

Audacity. :-
This is a free, easy-to-use audio editor and recorder for Windows, Mac OS X, GNU/Linux, and other operating systems. This can be used to: Record live audio, Convert tapes and records into digital recordings or CDs, Edit Ogg Vorbis, MP3, and WAV sound files, Cut, copy, splice, and mix sounds together, Change the speed or pitch of a recording.
http://audacity.sourceforge.net

WavePad :-
This is a audio editing software is a full featured professional sound editor for Windows. It allows anyone to make and edit audio recordings. Wjth this editing tool audio files can be cut, copy and paste parts of recordings and, if required, add effects like echo, amplification and noise reduction. WavePad works as a wav editor or mp3 editor but it also supports a number of other file formats.
http://www.nch.com.au/wavepad/index.html

MP3 Direct Cut :-
mp3DirectCut is a fast andreliable audio editor and recorder for compressed mp3 works. You can directly cut, copy, paste or change the volume with no need to decompress your files for audio editing. This can save encoding time and preserves the original quality, because nothing will be re-encoded. The built in recorder creates mp3 on the fly from your audio input. Using Cue sheets.
http://mpesch3.de1.cc/mp3dc.html

MPTrim :-
MPTrim is an easy to use MP3 editor. Can be used toimprove MP3 collections quality. mpTrim can trim MP3s - removing silent or unwanted parts. mpTrim can adjust the volume of MP3s. Volume change can be manual or automatic (volume normalization). mpTrim can fade-in/out MP3s (to fix abrupt beginning/ending). mpTrim can clean-up MP3s and will recover wasted disk space.
http://www.mptrim.com