Two dimensional convex hulls:
Animations of Graham's scan can be seen here
here (Princeton). Both these algorithms use angular sorted order
(as proposed in Graham's algorithm), as opposed to the x-sorted
order discussed in class.
Line segment intersection: An animation
of the line sweep algorithm can be seen here
Trapezoidal decomposition and polygon
triangulation: A Java applet for the triangulation of a simple
polygon can be seen here
(University of Bonn, Germany).
This applet illustrates the three-step process of trapezoidal
decomposition, subdivision of the polygon into monotone pieces,
followed by triangulation of the polygon.
Voronoi diagrams: An animation of
Fortune's line sweep algorithm for Voronoi diagrams can be seen here.
This page has links to other Voronoi diagram applets as well (scroll