A friend of mine turned me onto the http://audiocookbook.org, to look at what this guy has done in his sound processing experiments.
Using a product called Photosounder, he turns normal recorded sounds into bitmap images, and then tweaks them in Photoshop. He then re-loads the image in Photosounder, and saves them back as a digital sound file. The results are very interesting, to say the least! The picture shown here is a piano riff run through Photoshop's "Liquefy" filter. The photo is cool, and the sound is ... um ... liquidy?
Check out these links:
Original blog entry
Other examples of photoshopped sounds
The blog itself is a wealth of cool articles, especially for those of you that have ever played with a real synthesizer (oh, and for those of you that actually own your own music studios - you know who you are!) Most articles are equipped with an mp3 link that plays the sound being discussed, so its a very sensory experience I think you will enjoy.