Torsten has emailed about iAudioguide.com who offer free mp3 audio guides. At present there are guided tours of Barcelona,
You just need to save the .zip file to your PC then open it up. There’s several mp3 files in the zip plus a pdf map for you to print. Just copy the MP3 files onto your Smartphone or Pocket PC and you can then enjoy an audio guide of your chosen destination.
More cities are set to follow soon.