Hi guys,
Sorry my website (
http://www.kindle-screensavers.com/) was having some problems, but it should be working well now. If you need a place to host you screensaver don't hesitate.
And btw you can upload any colored image (it has to be larger then the targeted kindle resolution), it will be converted to grayscale and resize it.
If you have any improvement idea, or any question fell free to ask.