There are so many websites about nowadays relating to e-books and the Kindle and I think I have probably subscribed to them all. In fact so many that it's hard to keep up. However I have found one which lists all the free books for the Kindle. You can change it between UK and USA depending on where you live. I found it a bit easier than searching through on Amazon.
Today it shows 189 free books for the Kindle in the UK. It also shows books which have been reduced in price, and is updated hourly.
It's called E Reader IQ. So click the link and it will take you straight to it.