This is command primarily for doing balustrades quickly. Although, I guess it could have other uses...
1. Create a model from the baluster item you wish to use.
2. Run the command with: Right hand EDIT > Instances on curve
3. Select the model and then the curve.
4. An options dialogue will appear. The number of instances evenly placed on the curve is determined with a slider and their tangency by checking one or more checkboxes. (eg: how they relate to the curve)
In the image, "X" tangent was used.
Get it here.