Hello Kindle readers, Keyhole 8 is now formatted for the Kindle, and it is available from Amazon for only $1.99. Buy it here. 

William Walsh's Questionstruck is also available for $4.99, via Smashwords, which offers formats for various e-reading devices. You can buy it here. You can buy for the Kindle by downloading the HTML file and emailing it to your Kindle, and it will also be available in the Amazon store soon.