Note: It doesn't work for everything, and it can be hit or miss depending on your selection. If it doesn't look right the first time, try again with a slightly tighter selection, or one that is not so tight.
1. First, select the text or object that you wish to remove from your stock photo.
Make sure to select a bit of the background as it won't work properly if you select the object very tightly.
For this example, I used the rectangular marquee tool which is quick and easy for text, but for most other objects the lasso tool will work better.

2. Next, choose Fill from the Edit menu (or press Shift+F5) and choose Context-Aware from the drop-down menu.
Press OK. Your selection will magically disappear and be filled in with a logical blend which has been calculated from the surroundings and the rest of the image.
Press Ctrl+D to deselect the area.

3. Now in my example, I wanted to expand the background of my stock photo to fill up a signature sized canvas.
So, select Canvas Size from the Image menu, and widen the canvas.
You should have the new pixels be transparent, or if there is enough of a contrast you can use white as I did. (Because I didn't unlock the layer)

4. Select the newly created area with the magic wand tool, and again chose Edit -> Fill -> Content-Aware.

Ta-Da! Hope this helps someone out!