Yes, I have been infected by that marble virus too, I admit it. I had been looking for marble beads for a while and couldn't find any I liked. In the end making them myself by mixing black and white polymer clay was much easier than I expected.
I like that the result is always a little surprise.
In fact I'm working on a bigger (real) marble related project with my brother, but that will still take some time. Meanwhile I'll continue working on my little marbled beads collection!