Firefox: Google offers a host of really awesome services, but more than a few people are freaked out by how much information Google can gather. GoogleSharing anonymises your Google activities and keeps the big G out of your business.
GoogleSharing is a Firefox extension that routes all your Google interactions through proxy that taps into a swarm of Google identities — each query you perform through the main search engine, Google Books or other Google services is sent through one of the random identities.
As you would expect, GoogleSharing doesn't work for services you're logged into — it would have no effect on your Gmail session since you've willingly identified yourself to Google. For using Google services that don't require a login however it performs as promised. GoogleSharing can also function as a proxy manager, allowing you to add additional non-GoogleSharing proxies to use during your browsing session. GoogleSharing is a free extension and works wherever Firefox does.
Have your own tips or tricks for anonymising your web browsing? Let's hear about it in the comments.