Chrome/ Firefox: Google knows everything you've ever done, ever. The search giant has its hands in so many pots, it's hard to keep track- but all those ventures began (and, by and large, are financed by) the ubiquitous search engine. Other companies aren't as good as Google at tracking you, but that doesn't mean they don't try.
Disconnect is a simple browser addon that allows you to perform searches in Google and other search engines without leaving a trail. It's a small download with a light footprint. Once installed, it adds a button to your toolbar. You can search any incorporated search engine (currently Google, Bing, Yahoo!, DuckDuckGo, and Blekko) simply by clicking the icon, typing your search term, and hitting enter. Results, at least in my experience, will open in a new tab.
You can also incorporate Disconnect directly into your current search methods. The addon includes an option to filter search terms sent through Chrome's omnibox or Firefox's search bar, and an experimental option even allows you to use it directly from the search engine's site (google.com, say).
As proof positive of Disconnect's efficacy, when I searched through the addon, the resulting Google results page showed me as signed out, while, in other browser tabs in the same window, I was in fact signed in. This is the same functionality you can get from Firefox's "private window" or Chrome's "incognito" mode, without the added hassle of launching a window in those respective modes. It's also more effective: unlike those built-in features, Disconnect even blocks ISPs from tracking your search results, as well as pages to which the search results redirect.
The folks at Disconnect explain just how it all works:
First, we route your search queries through our proxy servers before they go to the popular search engines, including Google, Bing and Yahoo. Instead of these search engines knowing that a search is coming from you or your computer, all searches look like they’re coming from Disconnect.
Second, we prevent search engines from sending your search queries to the web sites you visit from search results pages.
Third, Disconnect encrypts your search queries, which prevents your Internet Service Provider (ISP) from seeing your searches.