Audacity

Audacity is a free, easy-to-use audio editor and recorder for Windows, Mac OS X, GNU/Linux, and other operating systems. You can use Audacity 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...And more!

http://audacity.sourceforge.net/

Wireshark

Wireshark (formerly Ethereal) is the tool of choice for network troubleshooting, protocol development, and education worldwide. Wireshark, a Network protocol analyzer, was written by an international group of networking experts, and is an example of the power of open source. It runs on Windows, Linux, UNIX, and other platforms.

http://wireshark.org/