BitKey is a bootable system image based on Debian containing everything you need to perform highly secure air-gapped Bitcoin transactions. You don't need to install it to a hard drive because it runs live from RAM.
Under the hood it contains a swiss army knife of handy Bitcoin tools that support a wide range of usage models, including a few very secure ones which would otherwise be difficult to perform. We created BitKey because we wanted something like it for our own use.
We're avid Bitcoin fans but after going to our first local Bitcoin meetup we discovered the elephant in the room was that there was no easy way to perform cold storage Bitcoin transactions where the wallet lives on an air-gapped system physically disconnected from the Internet.
The idea was to see if we could use the TurnKey GNU/Linux build system to create a self-contained read-only CD/USB stick with everything you need to perform Bitcoin transactions with as much security as you wanted - including highly secure air-gapped Bitcoin transactions.