Most people use watermarks to prevent the photo from being used by other people without consent. The best way to do it is to have it on the actual subject itself, but at a very low opacity. Once the photographer decides to sell/give the photograph away, he can always share the hi-res image without the watermark.
Having said that, it you want to have a watermark just to identify your images, then you can place it in a corner and reduce the opacity to about 10-15% so that it does not distract you from the image (example). Another thing you can do is to have a frame around the image and put your watermark there (example).