I don't own Amazon's best selling Kindle device (although I'd be happy to own one), but I do have the Kindle app on Windows Phone 7, Android and Windows. I've downloaded a handful of free titles of classic literature and a couple of full prices ebooks.
Having just installed the newly released app on Windows Phone 7* today, I had another look at the Kindle Store on Amazon.co.uk and was glad that I did because they're currently running a promotion with a selection of Kindle editions for only a pound each. I picked up five.
The promotion only runs until the 6th January, so if you want to pick up a bargain or two, act now. Remember you don't need a Kindle device to be able to read Kindle books - most decent smartphones, or even just a PC would do the job.
Head on over to The 12 Days of Kindle.
* Kindle for Windows Phone 7 link opens the Zune Marketplace, so only works on Windows Phone 7 or a PC with the Zune client installed.