FAQ:Visit Counter
From SailBlogs Support Wiki
How to add a visit counter to a blog page.
Premium Members Only
Premium members have the option to add custom side bar and footer options. With that, many users have been getting a free visit counter from SiteMeter. In addition, some of the services offer advanced tracking with paid memberships.
When you get your account sitemeter, it will give you a small code snippit. Add the snippit to the custom side bar block in the theme settings.
There are many similar services available.