A very kind blog follower has just let me know that The Guardian's free audio book download on Saturday was Stieg Larsson's The Girl with the Dragon Tattoo. The print edition is reviewed here on Euro Crime.
This is a free download of the abridged edition read by Martin Wenner (nb. 7hrs 26 compared to 18hrs 15m for the unabridged).
The offer is here but you've only got until 12 September.