As far as ranking signals (factors that score how sites are ranked) are concerned, Google has stated that they use hundreds of Ranking Signals. If I remember correctly Cutt's once stated there are some 400 signals they watch. Anyone doing SEO knows that these signals vary in importance. Most of these signals aren't going to apply to the average SEO. One guy above said it best when he compared contestants and said: "one contestant spammed and called it a day; while another (me) was using things he hasn't heard of." Obviously my results speak for themselves; however to understand why I consider so many ranking factors is really due to the type of SEO work I do. I specialize in extremely competitive niches and have a decent number of SEO companies that rely on me to get results for their more difficult projects. Its all the small things that add up that can be the difference between ranking #1 VS #2. With big competitive keywords this can be a significant difference in income. For example, I've seen one keyword at #2 generate $24,000 /mo but at #1 it jumped to $82,000 / mo. With this type of money on the line every ranking signal should be carefully considered. When I take on an SEO project I consider as many ranking signals as I can. From my experience I can confirm Google uses variables in their aglo and weighs different signals more or less for different niches and even for different keywords. These variables inevitably are why many get frustrated by SEO or have limited short-term success. I have a slight advantage in this area because of software we've created that monitors just over 100 ranking signals daily. I check and analyze that data constantly so I can remain effective for my clients and for my own projects. A lot of the major "algo updates" are actually simple adjustments where one signal is weighted more than another-- for example; the Penguin Update was mostly an Anchor Text adjustment. Yet, it took the industry months and months to figure it out. There are many many more ranking signals that could be discussed. I think the more SEO's that watch ranking signals (as many as they can) the better value they'll be able to offer to their clients. I was actually a little surprised that people hadn't heard about the Image thing or the Traffic Signals. These are relatively old news items that have been around for awhile. For most the Image OCR thing or the Traffic Signal probably aren't going to make much of an impact. It really depends on the strategy you use with it. For example a localized company can probably see some decent benefit from using their city name in images. ... but even then, I wouldn't suggest running out and making these changes to your sites unless it made sense. I'd have to review the niche/ keywords before I could comment on whether that ranking signal would add enough value to justify. The traffic signal on the other hand will generally help. But again, it depends on how its being used. Could you use different methods to boost traffic signals, yes! That's the best part about SEO, the more creative you get the more likely you will have an edge on your competition. You certainly don't need a bot or fancy software. SEO is about the big picture and not usually one thing. Its the combination of factors that can make one site more competitive than another and in turn outrank their competition. In the past you could get away with just building links and be fine. But today that strategy isn't enough for long-term results. Hopefully that has shed some more light on the "Ranking Signal" thing. Most ranking signals can be tested to determine how effective they are-- but it does get tricky trying to isolate one or two minor ranking signals. I'm constantly testing and considering new ranking signals and occasionally I come across some that provide huge value; but the vast majority are minor factors that provide small benefit by themselves.