You must have come across many photos that focus on a small part of the image while rest of the thing is just a blurry background. This is called the Tilt Shift effect. For example look at the picture below, it only focuses on the car and the street while everything else is just a blur.
Now look at the original photo:
Usually this would take a significant time and skill to accomplish but I will show you how to do it in less than 30 seconds. They key is a great tool called Tilt Shift Generator.
Once you have downloaded and installed the Adobe AIR based tool from here, simple open the image you want to create the tilt shift effect in. You will now see a small white circle over the picture, simple click on the area of the picture that you want to focus on. You will see that rest of the image will automatically go blur. You can also change the size of the focused area by dragging the big white dot at the border of the circle.
Dragging it clockwise increase the size of the focused area while dragging it anti-clockwise reduces it. You can also accomplish this by adjusting the settings on your left hand side.
This is it! Simply save the modified picture and show off.
Here is a short video where I have tried to create a Tilt Shift effect in the photos above.