What exactly have you tried and why hasn't it worked?

I tried generating random points around a set of random starting points, (without moritz' enhancement of a normal distribution around those starting points), but it generates sets like these. (Color coded for start point.)

As you can see, you tend to either get very concentrated groupings very separate, or widely spread groups that almost entirely overlap. Neither is representative of the kind of plots you get from real datasets that exhibit clustering.

moritz' enhancement might improve things somewhat--I'm trying it now--but if there were one or a few real datasets kicking around somewhere it would give me more confidence that I was performing a real test.