Adblock Plus
Right-click on a banner and choose “Adblock” from the context menu - the banner won’t be downloaded again. Maybe even replace parts of the banner address with star symbols to block similar banners as well. Or you select a filter subscription when Adblock Plus starts up the first time, then even this simple task will usually be unnecessary: the filter subscription will block most advertisements fully automatically.
NoScript
Winner of the “2006 PC World World Class Award”, this tool provides extra protection to your Firefox.
It allows JavaScript, Java and other executable content to run only from trusted domains of your choice, e.g. your home-banking web site, guarding your “trust boundaries” against cross-site scripting attacks (XSS) and Clickjacking attempts, thanks to its unique ClearClick technology. Such a preemptive approach prevents exploitation of security vulnerabilities (known and even unknown!) with no loss of functionality… Experts do agree: Firefox is really safer with NoScript ;-)
WOT (Web of Trust)
WOT, Web of Trust, warns you about risky websites that try to scam visitors, deliver malware or send spam. Protect your computer against online threats by using WOT as your front-line layer of protection when browsing or searching in unfamiliar territory. WOT’s color-coded icons show you ratings for 21 million websites - green to go, yellow for caution and red to stop – helping you avoid the dangerous sites. Surf safer and add WOT to your Firefox now.
Better Privacy
Better Privacy serves to protect against not deletable longterm cookies, a new generation of ‘Super-Cookie’, which silently conquered the internet. This new cookie generation offers unlimited user tracking to industry and market research. Concerning privacy Flash- and DOM Storage objects are most critical. This addon was made to make users aware of those hidden, never expiring objects and to offer an easy way to get rid of them - since browsers are unable to do that for you.