Audacity is just what you're looking for
http://audacity.sourceforge.net
.....but you're going to need wxGTK 2.4 from
http://wxwidgets.org/ in order to run it
don't use the 2.6 version because I haven't been able to get it to work with it (not even with backward compatibility) it so I don't recommend it, and you need to make sure you compiled it without unicode and without gtk2 support (which means you must have gtk 1.2.10 as well).....it all depends to what extent you are awear of your system.