Graduated Filters in Camera Raw [UPDATED]

I don't own a ton of camera gear. I've got my 60D, a couple of lenses, and a few other gadgets, but that's pretty much it. Something that's always been on my back burner to learn more about is just how filters work. ND filters, UV (which are arguably obsolete in the digital realm) and specifically Graduated Filters.

I know I've seen a million photos that have used a graduated filter, but I was never taught how to use one exactly, probably because I've never had access to one. I generally understand what is at work when using a graduated filter, but I just recently discovered that Adobe Camera Raw has a great graduated filter effect. I took these shots of a tree in a field not far from my house over the weekend. I got them home and was simply planning on adjusting the exposure and color balance for the sky until I got the result I was looking for. As I was kicking through Raw I found the graduated filter and decided to give it a try. Instant success. 

The original photo wasn't really worth posting, so you'll just have to take my word for it. The original sky in both of these was a very pale blue, almost white. As you can see/imagine, the filter brings the exposure on the sky down in the smoothest way. What's more is when you head to black and white, it's jet black. I love it. It's safe to say i went a little overboard on this first try, but I'm really liking the results.

[UPDATE]

Here are the original images. They've been converted to JPEG for web obviously, so the saturation got a little bit tweaked there, but this is generally what they looked like.