Blending in extractions with a gaussian blur:
A quick fix way to blend an extracted layer to the background and make it less ‘stuck on’ looking is to duplicate your extracted layer; on the bottom layer run a Gaussian Blur. You can see the subtle but effective difference this makes in the images below.
Andrei’s power tip:
You can achieve a similar effect by using Layer Styles and using a black Outer Glow on your extraction layer.