Real tilt shift lenses allow photographers to manipulate the focal plane of the lens in order to achieve different effects or to minimize things such as the unnatural look of a tall building when shot upwards from a low angle. One common use is to shoot from a high angle to achieve a miniaturized look.
I recently became aware of an online editing tool that mimics some of the features of a tilt shift lens and decided to give it a try. The image above was made with tiltshiftmaker.com/ from this original. Please view large for a better view.
While on the subject of tilt shift, this video by Keith Loutit is easily the coolest thing I have ever seen done with such a lens. I highly recommend checking it out; It's some super cool photography and a lot of fun too!
Photo taken in Elysian Park (Los Angeles, CA USA).