The front page is user powered and the content that shows on this page is filtered by users visiting the orginal signal aggregator page. The criteria for determining the popularity is a guarded secret, but could involve the number of clicks on a page, time period in which those clicks were generated and so on.
Original Signal is published by Stillpoint Media, a Dutch web publisher based in Amsterdam and is certainly a Web2.0 start page for many. One thing that it lacks is customization. I think if original signal enables users to customize and build their own web page it will be a lot more useful, but i guess that will be an act of encroachment onto personalized web page space.