Custom Charging Screen Image
While there already is a hack to add your own custom screensavers, this allows you change the images displayed when you connect your kindle to your computer.
I had got the usb networking hack on my kindle and was just looking around the filesystem when I noticed that the image file "USB_Charging_600x800.gif" in /opt/amazon/ebook/img/ui/ is the one that is displayed when you connect your kindle to your computer.
To change it, you will need to have already needed to install the usb-networking hack or have SSH over WiFi on your kindle to access the folder.
Connect as normal and make the filesystem writeable
root@kindle:/# mntroot rw
and navigate to /opt/amazon/ebook/img/ui/
(Its a good idea before you start messing around with the files in here, to back up the folder in case you overwrite something you meant to keep.)
The files that we are interested in are:
(or if you have a kindle DX)
Now in your image manipulation program of choice, design your new screen,
for mine, I went for a USB logo and a electrical symbol, but it can be anything as long as you save it as a 600x800 (or 824x1200 for DX) .gif file.
Note: If you want to match the font, it appears to be bold 35pt "Tunga" with -10% charecter width, and 35pt line spacing.
Name your two new images as USB_Charging_600x800.gif and USB_NotCharging_600x800.gif, then using a sftp client (eg filezilla), overwrite the old images in /opt/amazon/ebook/img/ui/ with your two new images.
Unmount and reboot your Kindle and you're all done!
There are some other interesting bits of images in /opt/amazon/ebook/img/ui/ that you could experiment with replacing with your icons and designs.