Bitcoin. It's nice work if you can get it. And if you get it...best keep that golden cryptocurrency safe from computer viruses and malware. Keyloggers and hackers. Your snooping friend Cornelius. Trezor, a hardware bitcoin wallet, considers itself a bitcoin vault impenetrable even to a gang of Ocean's Twenty, capable of protecting your stash regardless of security breaches in your computer or internet connection.
The Trezor wallet provides an "isolated environment for offline transaction signing" to ensure your private bitcoin keys stay locked on the device. Its front screen and pair of buttons give you visual verification of the transaction contents, and allow you to confirm or deny a signing. Back up the entirety of Trezor's contents on a small piece of paper (and stick that thing in a physical safe) to regain bitcoin access in the event of a disaster, wallet loss, or theft.
Trezor works on Windows, OS X, and Linux via a simple USB plug-in. Its code is open-source to ensure the bitcoin wallet "is absolutely transparent and backdoor free."