HarperCollins has 14 newly free books for Australian Kindle customers, under various imprints; most are pre-orders, but a few of the short stories are available now. These range from Children's books to those that are very definitely not for children, so I'll try to list a genre with them, below. I suspect most of these are pricing errors, so may go back up in price at any time (but if you pre-order while they are free, you won't be charged when they are delivered). If you are in Australia and have missed some of the earlier freebies, several are still free (although most are gone). Most of these are unavailable for those in the US (or are not free).
Children's Books- Dark Eden: Phantom File, by Patrick Carman
- Outlaw: The Story of Robin Hood, by Michael Morpurgo
- Sparrow: The Story of Joan of Arc, by Michael Morpurgo
Short Stories- A Piece of Time, by Traci Harding
- The Detox Factor, by Traci Harding
- Ghostwriting, by Traci Harding
- Curses, by Traci Harding
- The Lost Word, by Traci Harding
- The Limbo of Luxury, by Traci Harding
Very much NOT Children's Books- Beyond Temptation, by Lisette Ashton
- Make Me, by Charlotte Stein
- Surrogates, by KD Grace
- O for Obedience, by Lucy Salisbury
- Across my Knee: The Delights of Spanking, by various