Pretty sure Google Analytics does this for free. They can either split everything out into multiple sites or group them into one.
I think that there are some free plug-ins you can add to your page. It would not let you see the detailed amount of traffic on your site but just a counter of who visits.
I think that in most blogs, there are also some flag counters that would give you the count of how much traffic you get per country.
If that is what you are looking for, then there are a lot of those over the internet. But for something a little more detailed, I think you have to spend on those.