If you're a big user of Google (and face it, who isn't?), you'll want to install this Firefox add-on. It customizes Google in just about any way you can imagine, and no doubt in many ways you've never imagined. For a starter, it will block Google's ads as well as Google analytic cookies, which some people believe invades their privacy. Additionally, it anonymizes your Google userid and lets you turn off "clicktracking."
That's just the beginning, though. It adds links in your Google search results to other search engines, including Yahoo, Ask.com, Wikipedia, and others. It will also filter out search results from Web sites known to be spammers, and let you customize not just Google, but its various sites and features such as Gmail and Google News. In short, if you're a Google user and want to tweak the way Google works, make sure to download this one.
Note: This link takes you to Mozilla.org, where you can automatically install the file into your Firefox browser.