This ain't no geometric shapes or such, but here are some handy ones:
\(\displaystyle f(x)=\left\{\begin{array}{cc}0,&\text{if} \;\ x\leq 0\\1, & \text{if} \;\ x>0\end{array}\right\)
4−41−12−2
\(\displaystyle f(z) = \left\{ \begin{array}{rcl}\overline{\overline{z^2}+\cos z} & \mbox{for}& |z|<3 \\ 0 & \mbox{for} & 3\leq|z|\leq5 \\\sin\overline{z} & \mbox{for} & |z|>5\\ \end{array}\right.\)
Just for kicks.
\(\displaystyle \setlength{\unitlength}{1mm}\begin{picture}(60, 40) \put(20, 30){\circle{1}} \put(20, 30){\circle{2}} \put(20, 30){\circle{4}} \put(20, 30){\circle{8}}\\
\put(20, 30){\circle{16}} \put(20, 30){\circle{32}} \put(40, 30){\circle{1}} \put(40, 30){\circle{2}} \put(40, 30){\circle{3}} \put(40, 30){\circle{4}}\\
\put(40, 30){\circle{5}} \put(40, 30){\circle{6}} \put(40, 30){\circle{7}} \put(40, 30){\circle{8}} \put(40, 30){\circle{9}} \put(40, 30){\circle{10}}\\
\put(40, 30){\circle{11}}\put(40, 30){\circle{12}}\put(40, 30){\circle{13}}\put(40, 30){\circle{14}} \put(15, 10){\circle*{1}} \put(20, 10){\circle*{2}}\\
\put(25, 10){\circle*{3}} \put(30, 10){\circle*{4}} \put(35, 10){\circle*{5}}\end{picture}\)