Firefox

Firefox 3.5 sets the pace with dozens of new features, including the smart location bar, one-click bookmarking and blindingly fast performance. Avoid online scams, unsafe transactions and forgeries with simple site identity. View Web pages faster, using less of your computer’s memory.

Read more: http://www.smashingapps.com/2009/11/26/15-most-popular-free-software-i-am-thankful-for.html#ixzz2MCAxDYHu