These days, more and more people are becoming concerned about the amount of data Google collects about you. Sure, so far it looks like they have done nothing but acceptable things with that data, but times change. Just because the people in charge today run the company right doesn't mean that later arrivals will. Plus, there is no guarantee the government won't show up in their data centers. The Customize Google Plugin gives you some control over what data Google collects without messing up most functionality. As a bonus, it also allows you to customize certain settings and make those settings sticky without giving away your identity.
Pros:
- Free
- Anonymizes your Google ID
- Also filters Ads
- Provides ways to customize your Google experience
Cons:
- Causes functionality problems with a minimal number of services (default map location)
- Only works with Firefox (of course, if you care about privacy, you should be using Firefox)