Linux Kodachi!

Qubes is an open source operating system designed to provide strong security for desktop computing.

Whonix aims at preserving your privacy and anonymity by helping you use your applications anonymously. A web browser, IRC client, word processor, and more come pre-configured with security in mind.

BunsenLabs Linux is a distribution offering a light-weight and easily customizable Openbox desktop. The current release is Hydrogen, built on top of Debian Jessie. The project is a community continuation of CrunchBang Linux.

Subgraph believes that the best way to empower people to communicate and live freely is to develop technology that is secure, free, open-source, and verifiably trustworthy.

Lightweight Portable Security (LPS) is a Linux LiveCD developed and publicly distributed by the United States Department of Defense’s Software Protection Initiative that is designed to serve as a secure end node. It can run on almost any Intel-based computer (PC or Mac). LPS boots only in RAM, creating a pristine, non-persistent, end node. It is capable using Common Access Card (CAC) software for authentication into DoD networks.LPS-Public turns an untrusted system (such as a home computer) into a trusted network client. No trace of work activity (or malware) can be written to the local computer hard drive. As of September 2011 (version 1.2.5), the LPS public distribution includes a smart card-enabled Firefox browser supporting DoD's CAC and Personal Identity Verification (PIV) cards, a PDF and text viewer, Java, a file browser, remote desktop software (Citrix, Microsoft or VMware View), an SSH client, the public edition of Encryption Wizard and the ability to use USB flash drives. A Public Deluxe version is available that adds OpenOffice and Adobe Reader software. »

Freepto is a Linux-based operating system on USB stick. This means you can bring it with you and use any computer as it was your own. Also, data you save on the USB stick will always automatically be encrypted (i.e. nobody else will be able to access them).