I mentioned SpyFu in the Market Research section of the Rolodex but where it really shines is for PPC research. Rather than figuring out what keywords are profitable and which ads work the best through trial and error you can just use SpyFu to figure out exactly what keywords your competitors are bidding on and which ads they are running for those keywords and how long they have been running. Chances are if a competitor has been running an ad for a specific keyword for a period of time then it must be making them money… so you can just copy what’s working!