Julia Explorer is a small tool by Lex Spoon that sketches the Julia Set associated with any specified point in the Cartesian plane. It is an improvement over many fractal exploration programs because the point is selected visually instead of with decimal numbers. Here's what the tool looks like:
Interaction is simple. The blue dot corresponds to the Julia Set's parameter point. Click in a new location to move the dot. The tool has a tradeoff of speed versus image quality; one can click on the "NumPoints" text to play with this tradeoff.
Julia Explorer is available for Linux/x86, Wintel, and (at one time) MacOS: