W3Counter is the most powerful traffic counter I found. It tracks almost everything you need to know, like unique visits, search terms, locations of visitors, referrers and more. There is a Live View page showing real time data, such as Online Now, Twitter Mentions.
W3Counter offers free and pro accounts. As free account, you can track 1 website and up to 5,000 page views per day.
You need to sign up to use W3Counter service. After sign up, enter information of your website to create the counter:
Here is your tracking code, paste it on your website.
If you are using WordPress, you can install the plugin of W3Counter. Search Blog Stats by W3Counter plugin and install it.
Go to Settings, find W3Counter, Enter your website ID and W3Counter account information.
You can now check out your stats report on W3Counter or directly on WordPress Dashboard.