Clickablenow has one catch, everyone needs to run this as a Firefox/IE/Flock extension to get the benefit from the ability. Once installed, the backgrounds of Twitter become a playground. Any image you wish to make a clickable hotspot is possible.
They use oAuth for authentication and once logged in, your Twitter background is brought in to work with. You simply drag and drop links into your background. Unless they have the extension, there is no difference. With the extension, you can make anything a clickable area! A great way to finally share links of the information you place in your background.
They make a point to tell you the bigger screen resolution the better so you can see more background area. It makes perfect sense as the tiny screens block most of what you would want to show and link anyway.
Stats showed this as an experimental add-on with just under 2,000 downloads at the time of writing. So test it out and let us know your thoughts!