One of the most useful Photoshop skills you can have is the ability to convincingly replace the sky in an image. This great tutorial will show how to do just that, from placing and masking the sky in to blending it effectively.
Coming to you from Nathaniel Dodson of tutvid, this helpful video will show you how to swap out a sky in an image. Living in Cleveland, I'm pretty used to drab, gray skies that can kill an otherwise interesting shot, and learning how to swap out a sky for something even slightly more interesting can make a huge difference in the final result and the number of usable shots you walk away with (I'll sometimes add something as simple as some broken clouds to spruce up an image). And it's not just a useful skill for landscape work; if you like to shoot natural light portraiture, particularly images that show wider views, it can be a great way to improve a shot or add a sense of drama. Even if it's not something you plan on doing very often, it's a beneficial way to flex your Photoshop muscles this weekend, so grab a shot with a dull sky and get to work!