If its a wordpress blog you can get a stats plugin, which is very useful.
I think i will choose its either Google Analytic tool or StatCouter.
Piwik - Web analytics - Open source - Open Source Analytics
You can check your blog traffic after detecting strange search traffic signals during routine maintenance of ckecking.You can check out the full directions here. While this job is done by Google Analytics which is free.
You can add Google Adsense to your Blogger blog as well. Here is how to do it
Log into Analytics and click on Add Website Profile.
Enter the website address (URL) of your blog here.
Copy the html code they give you.
Go to Blogger and choose Layout then Edit Html.
Scroll to the bottom of the html until you see the </body> tag.
Paste your Anayltics code right before the </body> tag.
Save and go back into Google Analytics to see if you have installed the code correctly. If you have you’ll see the message Receiving Data. If not you see Tracking Not Installed. Sometimes it does take a while for the tracking code to be picked up by Google – so wait a few minutes to see if it changes after an hour or so. If it doesn't check that you entered the code correctly.
Google Analytics and Clicky are the two I use.
I recommend Google Analytics for measuring your sites traffic. As it is the most trusted and has easy to navigate features which many SE optimizers will loved. ♥♥
Google analytics may lag a couple of hours sometimes, but it is the most reliable source.