The NinjaStik is a bootable USB 3.0 memory stick. It allows to you boot your computer into an anonymous operating system (via custom firmware and Linux-based OS).
There are a host of privacy-related tools on the stick — including a Tor Browser, a Bitcoin Wallet and Thunderbird with Enigmail installed.
According to the company the Ninjastik can be used a PC or Mac (but must have Intel processor and must be able to boot from USB).
You can read the NinjaStik FAQ here.
Prices for the NinjaStik start at $56.95