Non-blocking UI's with interface previews
Pinterest does something really clever related to this - not so much for data placeholder but for images. They have precomputed the dominant color for each image and show that color while the image loads.<p><a href="http://littlebigdetails.com/post/56782380031/pinterest-before-image-is-loaded-the-background" rel="nofollow">http://littlebigdetails.com/post/56782380031/pinterest-befor...</a>