"A free yet reliable invisible web tracker, highly configurable hit counter and real-time detailed web stats. Insert a simple piece of our code on your web page or blog and you will be able to analyse and monitor all the visitors to your website in real-time!
- Free, Fast, Responsive, Quick loading and Reliable Service.
- Invisible Tracking - no ads on your website.
- Accurate real-time website statistics with detailed visitor tracking and analysis."
I haven't tried WordPress but if I recall right I think it comes reinforced with web tracking services so WordPress users probably won't need this while it's highly recommended for Blogger users.
All you need is to register and start a project for your site then embed the code within your HTML editor.
Like for example my code is embedded on the bottom of the page right underneath the Visitors Map. See the little gray digits? That's StatCounter.