Are you wondering how much traffic can you expect by building a website around a specific keyword or key phrase?
Google Traffic Estimator can help you with that. It might be one of the very few tools that gives you traffic estimates that you can trust. These estimates are believed to be based on system-wide AdWords performance information, and it will give you information about the average CPC, maximum CPC, estimated monthly search volume and the number of clicks per day that you can expect.
There’s a lot of tools with this functionality out there, but in my experience they’re often just providing “guesstimates” and that’s not good enough. Google Traffic Estimator on the other hand has been pretty reliable and I can only recommend it.