Firesheep makes hacking your fellow cafe-goer a simple, user-friendly, DIY affair. Firesheep takes advantage of a lack of end-to-end encryption, allowing hackers to grab cookies, the snippets of code that indentify your private information. This, in turn, enables hackers to masquerade as you on sites like Facebook, Twitter, Amazon, or eBay. Over a million people have downloaded the program. (Fast Company covered Firesheep months ago.)