With the ever growing complexity of modern day web browsers, there follows new and dangerous exploits for them. To get around this there exists a variety of plugins for the popular browsers. These plugins attempt to increase your security on the net no only against malicious attacks but also against companies tracking your usage.
Another useful tool is Ghostery http://www.ghostery.com/ . This program blocks most of hte popular tracking methods that websites use to gather information. Whether they be plugins, scripts or tracking bugs. The program notifys you of when its found something and pops up in the corner what they are. It allows you to then click on them to find out more about what that particular tracker is and what it does. This program has a lot of overlap with Noscript in that usually noscript blocks them before it does. Ghostery works with all of the popular browsers.
The last one is Priv3 http://priv3.icsi.berkeley.edu/index.html . This disables all of the buttons for social network sites on other websites. These buttons enable the social network sites to track you on the internet even when you don’t click on any of them. So if your looking for more privacy this might be useful. Again noscript tends to block these already. Priv3 is currently only for Firefox.