A friend of mine once needed kind of a cake to visualize fractions. Adding rotated nodes wasn't hard:
\documentclass{scrartcl}
\usepackage{tikz}
\usetikzlibrary{intersections, calc, fpu, decorations.pathreplacing}
\newcommand{\TikZFractionalCake}[5]{% Num, Denom, Color, Borders, Size
\pgfmathsetmacro{\angle}{360/#2};%
\foreach \x in {1,...,#1}%
{ \pgfmathsetmacro{\lox}{\x-1}%
\filldraw[draw=#4,fill=#3] (0,0) -- (\angle*\lox:#5) arc (\angle*\lox:\angle*\x:#5) -- cycle;%
\pgfmathsetmacro{\mix}{\x-0.5}%
\node[rotate=\mix*\angle] at (\mix*\angle:#5+0.3) {\x};
}
}
\begin{document}
\begin{tikzpicture}
\TikZFractionalCake{20}{20}{white}{black}{3}
\end{tikzpicture}
\end{document}

Sure, makes it even easier:
\documentclass{scrartcl}
\usepackage{tikz}
\usetikzlibrary{intersections, calc, fpu, decorations.pathreplacing}
\newcommand{\TikZFractionalCake}[5]{% Num, Denom, Color, Borders, Size
\pgfmathsetmacro{\angle}{360/#2};%
\foreach \x in {1,...,#1}%
{ \pgfmathsetmacro{\lox}{\x-1}%
\filldraw[draw=#4,fill=#3] (0,0) -- (\angle*\lox:#5) arc (\angle*\lox:\angle*\x:#5) -- cycle;%
\node[rotate=\x*\angle] at (\x*\angle:#5+0.3) {\x};
}
}
\begin{document}
\begin{tikzpicture}
\TikZFractionalCake{20}{20}{white}{black}{3}
\end{tikzpicture}
\end{document}

That is possible indeed:
\documentclass{scrartcl}
\usepackage{tikz}
\usetikzlibrary{intersections, calc, fpu, decorations.pathreplacing}
\newcommand{\TikZFractionalCake}[6]{% Num, Denom, Color, Borders, Size, k-th label
\pgfmathsetmacro{\angle}{360/#2};%
\foreach \x in {1,...,#1}%
{ \pgfmathsetmacro{\lox}{\x-1}%
\filldraw[draw=#4,fill=#3] (0,0) -- (\angle*\lox:#5) arc (\angle*\lox:\angle*\x:#5) -- cycle;%
}
\pgfmathsetmacro{\secondstep}{2*#6}
\pgfkeys{/pgf/number format/.cd,int detect,precision=2}
\foreach \x in {#6,\secondstep,...,#1}%
{ \node[rotate=\x*\angle] at (\x*\angle:#5+0.3) {\pgfmathprintnumber{\x}};
}
}
\begin{document}
\begin{tikzpicture}
\TikZFractionalCake{21}{21}{white}{black}{3}{3}
\end{tikzpicture}
\end{document}
