If you're in the early stages of your relationship with artificial light and light modifiers the Light Shape Comparison offered by Bron Elektronic has a ton of visual comparisons between different lighting equipment. Obviously they're only showing equipment they manufacture but the basic comparisons are extremely helpful. Side by side identical shots show you what a portrait taken with a conical snoot looks like compared to one taken with a ringflash or a reflector or a silver umbrella, or any of several other lighting options.

Via Strobist