Wow! Now this thing is cool! A new app for $30 you can download for an iphone which uses the built-in microphone and hardware to turn it into a portable a real-time spectrum analyzer and oscilloscope. For those that have an iphone it's a quick and convenient way to do basic room analysis or measure equipment. Snapshots can be saved at will and saved for later. I have not used it seriously yet, but so far it seems to work very well and is very sensitive.

Signal Scope