Hiroshi Miyazawa of Macromedia has developed a new AutoShape for Fireworks MX 2004 called Wave.

The Wave Auto Shape is basically an adjustable sine wave. You can change the number of cycles, and adjust the size of the shape, thereby changing the period and amplitude of the wave.

At present this extension is only available to download from the CommunityMX site although I’m sure in time it will appear on the exchange.