The polar library allows to draw polar axes and plot types relying on polar coordinates, represented by angle (in degrees or, optionally, in radians) and radius.

The code is from the PGFPlots 1.10 manual: “5.9.1 Polar Axes”.

Polar plot

Edit and compile if you like:
	% equivalent to (x,{sin(..)cos(..)}), i.e.
	% the expression is the RADIUS
Click to download: polar-axes.texpolar-axes.pdf