Audacity is near perfect for recording and editing sounds. It is available for Mac OS X, Microsoft Windows, GNU/Linux, and other operating systems. It is open source software, therefore free. It features:

• 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.
• Import and export many different formats.
• Fast editing of large files and unlimited undo/redo
• and much more…

I have been using audacity for a while and highly recommend it to any looking for a program to record and edit sound files. Check out Audacity or download it now.