A quick search turned up a lot of links, but not much textual information on the bikes themselves. Looks like they're running 1:1 on custom-made bikes. Here's two collections of links to pages maintained by local clubs and individual riders:
http://freenet-homepage.de/kunstrad/links.htm
http://www.cycleballer.com/1232.0.html
And two online shops with galleries - they both seem to be popular manufacturers:
http://www.starbicycle.com/fotos.htm
http://www.otoupalik-bikes.cz/index_de.htm
"Artistic Bicycles" are Kunstrad bikes, "Cycleball" or "Radball" frames look like this:
Check out these videos if that frame has you muttering under your breath:
www.youtube.com/watch?v=PgiGsWf6iYI
www.youtube.com/watch?v=qO8xBlkumYM
http://www.myvideo.de/watch/797254