So I created work/konsole4-ui to work on porting Konsole to XMLGUI (and LiveUI?). I'm also using as a test area for some ideas and code cleanup. So far so good, I got the session menus to work. The shortcuts are an issue I have to look into again. Things will be much better when I can actually run KDE4 so I can test session managment, config files, etc...
Many thanks to Robert Knight who has been doing a lot of work on Konsole' backend for KDE4.
I like APOD images and in general cool outer space images. I wanted to place these small images (400x400) on my KDE desktop in a certain location that didn't have anything else there. How to do this? No idea... 
I couldn't find a single program KDE or not to handle this. KDE3 KControl/Background has a few issues... urgh! I hope KDE4 is "better".
Anyway, since I've coded KDE kdesktop/background DCOP before, I threw together a DCOP call to position an image on KDE's desktop. It is not perfect and it won't go into KDE3. But it works... 
void setWallpaper(int desk,QString wallpaper,int X,int Y)
dcop kdesktop KBackgroundIface setWallpaper 1 %s 400 0
The %s will get changed to the image... pretty cool!
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Possible solution
I did once put a webcam image into the background doing roughly the following:
Every minute a script fetched the webcam image. Then with the help of some ImageMagick I composed a background image combining my usual background with the webcam image. This combined image was then moved to a special folder in two copies. KDesktop was then setup to cycle through the images in the special folder. Yes, it's an awful hack but it did what I wanted.
SuperKaramba maybe?
there are at least 4 photo widgets for superkaramba. At least one of them would work fine for you, no or very little hacking required.
I found these in first 3 pages of Karamba section on kde-look.org
a-foto
comics
Riding With Robots - which is almost exactly up your valley.