ShadowCaster also has the ability to blend shadows via the Burn Shadow tab. Nice little feature for overcoming the fact that InDesign doesn't, as yet, support transparency beyond simple clipping paths. So, using the Burn function, you can actually transfer a portion of your image onto the shadow itself, so you don't have to worry about the artifacts that can be associated with gradients and clipping paths. You can also pick the mode of the transfer for special effects. These include:

• Darken, which compares overlapping pixels and keeps the darker of the two;
• Multiply, which multiplies the values of overlapping pixels;
• Lighten, which compares overlapping pixels and retains the lighter ones;
• Screen, which multiplies the inverse values of the pixels;
• Normal, which substitutes the values of all overlapping pixels with the shadow;
• Add, which adds pixels together for a darker pixel;
• Subtract, which subtracts the pixels together for a lighter pixel;
• Replace, which compares overlapping pixels and replaces them with the
  shadow's color and shade.

Burned images must be TIFFs, and they must be grayscale. (The ShadowCaster Burn Shadow tab provides feedback to let you know when all of the criteria for burning have been met.)

The bottom line
It should occur to you that you can, of course, accomplish the same effect in Photoshop or another image editing application, then import the effect into InDesign as you would any other image. However, I find ShadowCaster to be a helpful time saver with some genuinely valuable features and an intuitive flow. I also appreciate the feedback provided in ShadowCaster's Image Attributes panel, which includes file path, size, type, etc. for any image in InDesign, not just the shadows created by the plugin.

The shadows created with ShadowCaster are of high quality; you get a lot of control over the shadows, including the ability to blend them; the performance is zippy; and the price is pretty reasonable. I give ShadowCaster a buy recommendation.

ShadowCaster for InDesign requires Adobe InDesign 1.5 or higher (Mac or Windows). It costs $99.95. For more information, visit http://www.alap.com.