Blurring an object in the foreground of a photo
One of my class members, Falon, asked me how to blur the rocks in the foreground of her beautiful photo:

I have helped people blur backgrounds many times, but foreground blurring isn’t so common. While the two techniques are similar, it goes without saying that the layer order is a bit different.
STEP 1: THE SETUP
Duplicate the Background layer twice, and call the copied layers "Clone" and "Blur" respectively:

(Note: If you’ve already done some editing with adjustment layers, that’s ok. They can remain above these layers, but I recommend turning them off while you do this work.)
STEP 2: THE BLURRING
Apply a desired amount of blur to the "Blur" layer. If you have Photoshop, I strongly urge you to begin by turning the layer into a Smart Object, so that you can adjust the amount of blur later if you desire. However, if you have Elements you can’t do this; that’s ok, just apply the blur directly to the layer.

STEP 3: THE CLONING
Turn off the "Blur" layer, then choose the "Clone" layer.

The goal here is to carefully clone away the edge of the rock (or whatever item you’re blurring). You need to clone it further than the edge of the blur will reach. So if, on your screen, the blurring spread the edge by about 1/4 of an inch, you should clone away 1/2 an inch to be safe.

(Note: Make sure your Clone Tool is set to "Sample: Current & Below" in the Options Bar.)
Take plenty of time to do this. It has to be done well. Any straight lines that exist have to be continued plausibly. If you take a look at my clone result below, see how I’ve created a nice straight believable waterline on the left-hand side, where the rock used to be?

STEP 4: THE MASKING
Turn the "Blur" layer back on, and add a mask to it.

Then mask out the entire background, so that your foreground item (rocks in this case) is the only thing visible on the blurred layer. When you are masking around the rocks, make sure you ALWAYS use a soft brush (Hardness 0%) and choose its size wisely to retain a plausibly blurred edge. In this screenshot, I’ve hit the key to show you my mask in red:

And here is my end result:
