The Trezor Wallet is a hardware-based Bitcoin Wallet that can be connected to the computer via USB port. Hardware wallets are one of the safest ways to store Bitcoins and Altcoins. The private key is held on the Trezor Wallet. Sending Bitcoins is done through the external wallet and manually acknowledges each transaction via the Trezor Wallet.
The Trezor Wallet is developed and distributed by the Czech company SatoshiLabs and currently costs about 90 euros.