Drawing a partitioned set with TikZ

I'd like to create a graphic of a set partitioned into subsets of various sizes/shapes/colors. (I'm trying to show a set partitioned by an equivalence relation into disjoint subsets, i.e., the equivalence classes).

I was hoping to find something on http://www.texample.net to give me an idea of a good method, but I'm having trouble finding any examples. Does anyone have any suggestions?

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Welcome to TeX.sx! You don't have to sign with your name since it automatically appears in the lower right corner of your post. – yo' Jan 11 '13 at 18:13
If you only want a shape divided in some way, why not to draw a simple circle with radial cuts? – Sigur Jan 11 '13 at 18:24

\begin{tikzpicture}