Thought I'd toy with hacking the Kindle since it seems pretty straight forward (and safe).
I wasn't looking for anything fancy, just using my own screensavers was the only justification I needed.
(Note: You will see some references to 3.2.1 Kindle firmware, but most of us will be on v3.1. The 3.2.1 firmware is for a sponsored version of the Kindle that has adverts sent to it, as far as I can make out.)
If that's all you want to do it's pretty straight forward.
First off you need to to is apply the jailbreak update, which can be found here:
http://www.mobileread.com/forums/showthread.php?t=88004Note: All the hacks are reversible since the unistallers are also included with the installation files.

The
kindle-jailbreak-0.9.N.zip file contains all versions.
I have a standard WiFi only one, so I just need to dump the
update_jailbreak_0.9.N_k3w_install.bin file onto the root of the Kindle (via USB) and then upgrade the firmware [Menu>Settings>Menu>Upgrade]
(k3gb is for the Kindle 3 with 3G)
Once it's rebooted, you need to bung on the hack for changing the screensavers, which I got from here:
http://www.howtogeek.com/howto/37424/jailbreak-your-kindle-for-dead-simple-screensaver-customization/Same as before, all version are in the one .zip fil. In my case I needed the
update_ss_0.20.N_k3w_install.binUpdate/reboot the kindle same as before and now you will see a new folder named
linkss, this is where all the screensavers go. (the old ones (in .gif format) are in a folder called
backups)
A quick word on the format:
All screenies are 600 wide by 800 tall in 8 bit grayscale, and you should save them as .PNG's.
There's a pile of pre made ones here:
http://kindlewallpapers.tumblr.com/archiveAll you do is drop your new screenies into the linkss/screensavers folder and reboot for them to take effect.
Note: For it to randomly select images you need to create a file called
random without a file extension in the linkss folder. So make sure you have Show File Extensions enabled, create a text file called random.txt then remove the .txt bit.
If you want to go a bit fancy and add the 'Slide Power To Wake' bit to the bottom of the images, then this bloke has written a wee Photoshop batch file you can use.
http://www.mobileread.com/forums/showthread.php?t=108068Seemples.
