The order of the ring is changed every seven (7) days.  Sites are 'staggered' based on the amount of traffic they appear to be getting.  Larger (higher traffic) sites are placed after low-traffic sites and low-traffic sites are placed after high-traffic ones, making the experience of "travelling the ring" more interesting, and also helps lower traffic sites receive more visits.  If you're looking for a particular site, just click "List Sites" from any site on the Ring.  Navigating the web for San Francisco is now easier than ever!