XaoS (pronounced chaos) lets you dive into fractals in one fluid, continuous motion. It has many other features like a wide array of different fractal types and coloring modes, autopilot, random palette generation, color cycling, and animated tutorials.
XaoS is easier to experience than explain, so give it a try! Point at an area you want to explore in the image below and hold the left mouse button to zoom in. Gone too far? Hold the right mouse button to zoom back out.