The following list contains links to other sites that contain information about Penrose tiles and/or quasicrystals.
Roger Penrose
Some information about the man behind the tilings.
QuasiTiler
An application that generates Penrose tilings using the fat and thin Penrose rhombuses.
Penrose Tilings and the Golden Mean
A page by Tony Smith that gives a nice introduction to Penrose tilings.
Aperiodic Tiling with Penrose Rhombs
Make your own set of Penrose Rhombs.
Penrose Pavers in Penngrove, CA
Some people made a garden path with concrete Penrose tiles.
Clusters And Decagons
New rules for constructing quasicrystals.