Here are links to Geometry related sites:

An interesting set of geometry related investigations can be found at Imath

MathOpenReference: A slew of geometry information and tools. All free and online.

Constructions and plenty of sample problems to help you understand the concepts:

• Introduction to Geometry
• Angles and Lines
• Conditionals, Unions, and Intersections
• Measurement Formulas
• Constructions
• Greek Prefixes for polygons/polyhedra (from Virtual Polyhedra, a GREAT geometry site)
• Glossary
• Sample problems
• Stereograms: an Application of Geometry

Cinderella Interactive Geometry Software: Geometry on the desktop and the web. Version 1.4 is free.

GeoGebra is a wonderful tool. An entire Geogebra wiki has been developed around the tool. See the geometry sections for online tools, problems and examples.

The following links can be found at math.com

Geometry Building Blocks Geometry words Coordinate geometry Pairs of lines Classifying angles Angles and intersecting lines Circles	Polygons Polygon basics Triangles Quadrilaterals Area of polygons and circles
Relations and Sizes Congruent figures Similar figures Squares and square roots The Pythagorean Theorem and right triangle facts	Three-dimensional Figures Space figures Prisms Pyramids Cylinders, cones, and spheres
Tables & Formulas Calculators · Polygon PropertiesNEW! · Area Formulas · Volume Formulas · Surface Area Formulas · Circles - Definitions & Formulas · Perimeter Formulas · Circle A portal covering a wide variety of geometry topocs can be found at Math Open Reference Topic include: Plane Geometry Introduction to Plane Geometry Points, lines and planes Angles Parallel lines Triangles Quadrilaterals Polygons Congruence Similar polygons, triangles Circles and Arcs Ellipses Constructions Famous Geometers Coordinate Geometry Introduction to Coordinate Geometry Points, lines and planes Polygons Circles and Ellipses Transformations Solid Geometry Cubes Cylinders

EXPLORING ADVANCED EUCLIDEAN GEOMETRY with Geometer's Sketchpad by Gerard A. Venema may be downloaded as a sequence of pdf documents. The size of each file is 0.2MB or less. There are a total of 121 pages in all.