Polar Cursor Theme is a smooth and simple cursor set created primarily in Inkscape.
There are three cursor sets included in this package. The default with the orange busy cursors is called PolarCursorTheme and the blue and green variants have -Blue and -Green added to the end of their theme name. To make sure that all themes are installed (or only the one you want) extract to /.icons/ in your home folder.
KDE users please note that installing the cursors through the control center can cause some cursors to use the default X cursors. To fix this simply extract the theme directly to /.icons/ in your home folder.
Finally a special thanks to all the authors of various cursor themes here on gnome-look.org for ideas.