TrueCrypt - Free Open-Source On-The-Fly Disk Encryption Software for Windows 7/Vista/XP, Mac OS X and Linux.
What if modern technology provided a way for a lawyer to carry around every form, document and pleading and paper he ever created in his career, and gave him a way to index and find them on a moment's notice? Well, it has and I carry every scan, every form, and every document I have ever created in the many years of practice on a 64 Gigabyte USB stick that is no bigger than my thumb. That is why they are called thumb drives. But, what, you say, about security? What if you lose the drive? Why, there is a free, open source, answer to that question. TrueCrypt can create an encrypted volume of any size on any USB drive. Mine is 58 Megabytes, which is enough to hold all of my files, with plenty of room to spare. I also have made backups of every poem I ever wrote, every photo I have taken in the last ten years, and much other important stuff. Have you encrypted your stuff lately? Remember what George Carlin said: "We all want a place for our stuff". Don't just lock the door. Encrypt the sucker.