This is the device that converts audio tape cassettes into MP3 files and stores them directly onto an iPhone or iPod touch. It accepts most iPhones and iPod touches, and normal or chrome cassette tapes. With its free app, conversion to MP3 is as simple as inserting a cassette, docking an iPhone or iPod touch, and pressing play. » The Cassette To iPod Converter

SoundMeter has arrived to turn your iPhone into a handheld sound level meter (SLM). The iPhone’s built-in and headset microphones exhibit a remarkably flat frequency response, making them suitable for basic sound level measurements. However, due to sample rate limitations and frequency response degradation, SoundMeter is not recommended for use with the built-in microphone of first-generation iPhones.
» App Store – SoundMeter