Where I say "foto's" I mean "photos" off course!
Sorry my englisch is not that good.....

You could use the built in C5 slider, like this:
http://www.concrete5.org/marketplace/addons/image_slider/...

Or for single images you could use this:
http://www.concrete5.org/marketplace/addons/random-image/...

I want to pick random photos from many different file-sets.

You could try creating a fileset called 'random'. Then click images from other file sets and add them the new fileset 'random'.

Images can be in lots of different filesets.

Thanks. I thought about that too.

You can create such banners with my addons Uber List and Magic Data.

The process of creating the list is essentially:
List a list of filesets. Shuffle it. Then for each fileset in the list, shuffle it and take the first.
(You can create a Magic Data expression to do that within Uber List)

Uber List can then pass each file to a stack or html fragment that wraps it up for display.

Currently in the PRB I have Sorcerer's Gallery which makes such a process easier. You would only need to do the listing part (as per Uber List), but not the wrapping up for display part because the gallery templates take care of that.