Heat maps (Crazy Egg)
Showing you concentrated mouse activity on your webpage, this is extremely helpful in giving you a visual overview of where users are clicking. Every time you redesign your site you should run a one-month heat map to see the results. This is particularly helpful when selling advertising space or trying to find problem areas with your website. Plans start @ $9 monthly and I only suggest taking a 30 day picture each time you change a design.
Confetti maps (Crazy Egg)
Similar to the heat map, the confetti view offers a deeper picture into click patterns. The main difference here is that each piece of confetti is colored to match a referring URL in the accompanying legend. What’s cool about this is that you can see different patterns coming from different URLs. Plans start @ $9 monthly including the above heat map and I only suggest taking a 30 day picture each time you change a design.
Google analytics (Google)
Most people already know about Google analytics and probably already use it. Needless to say it’s free and it gives you an amazing overview of your traffic patterns. Some of my favorite stats include the time spent on your site, bounce rate (the percentage of people who leave your site quickly), unique visitors and of course referring URLs.
Google Webmaster tools (Google)
Many people I speak to do not use this free tool. I like it because it gives me a picture of my ranking and my links as Google sees it. More importantly it allows me to see any broken links or issues that Google has finding my website. Following the simple instructions on this website will definitely help you to reduce the friction between your site and Google. The statistics it provides will also give you some very good insight into how your site fares within Google.