Audio Analysis Creates Landscape

flight404 have a very nice example of what can be done in real-time within Processing in terms of audio analysis and graphcial creation.
The audio signal is analysed and the resulting FFT data is manipulated to make it a bit more manageable and then used to create graphics that resemble a landscape scene - all done in real-time.

Audio-generated landscape from flight404 on Vimeo.

Free audio editor

If you're looking for a free audio editor you might want to have a look at wavosaur.
It supports .wav and .mp3 files, has analysis tools, batch processing and VST and ASIO support.
Best of all it doesn't require an installer so could be run from a memory stick!

Sonic Visualiser

Sonic Visualiser is a free application that lets you analyse a recording in a variety of different ways.

"The aim of Sonic Visualiser is to be the first program you reach for when want to study a musical recording rather than simply listen to it.

As well as a number of features designed to make exploring audio data as revealing and fun as possible, Sonic Visualiser also has powerful annotation capabilities to help you to describe what you find, and the ability to run automated annotation and analysis plugins in the Vamp analysis plugin format – as well as applying standard audio effects.

We hope Sonic Visualiser will be of particular interest to musicologists, archivists, signal-processing researchers and anyone else looking for a friendly way to take a look at what lies inside the audio file."