Starting from the end
That's my Kindle in the screenshot running a full screen terminal. I'm about to run nmap (a network mapping program) inside a chrooted Debian ARM installation I put on the device. Having Debian on the device isn't really necessary for hacking the Kindle but it does make it easier to install ARM binaries of just about any of the 25,000 packages in Debian. Yep, apt-get works on my Kindle!