I'm sure you know about HDR. Just in a case, you can find information on Wikipedia
Here I'd like to share an easy HDR Effect technique that helps to improve your existing photos just with some clicks in the Photoshop. It is not my invention, I found the instruction on Flickr in KolNedra's set.
But I've used it and I'm pleased with the result:
1. Open your photos in the Photoshop.
2. For better understanding of the process, let's name the original Layer (probably it's called Background at the moment) as Layer 1.
3. Duplicate Layer 1 and name a new level as Level 2. Level 2 should be above Level 1.
4. Change the Blending option of Layer 2 to "Overlay". Stay on it.
5. Go to: Image > Adjustements > Desaturate.
6. Then: Image > Adjustements > Invert.
7. Go to: Filter > Blur > Gaussian Blur (around 40 pixels).
8. Now duplicate Layer 1 again, name a new layer as Layer 3 and place it above Layer 2.
9. Change the Blending option of Layer 3 to "Linear Light".
10. Give Layer 3 an opacity around 60%. And you're done!
For better results, tweak the percentage and play with Blending option of Layer 3 - see results with Vivid Light, Hard Light, Soft Light etc., and choose what you like.
I've got some photos, processed with this technique here in DT, as well as if you'd like to see more, you can have a look on photos in my personal blog post
. Hope it will be helpful!