Ivie Technologies from Lehi Utah USA have released a sound level meter that uses an HP iPAQ as the processor. The IE-33 is supplied with a Type 2 (Type 1 is optional) microphone and the software can calculate: narrowband FFT, 1/1 1/3 1/6 octave bands, NC curves, chart recorder. The unit also has an in built signal generator.
Read more on the Ivie web site.