Windows only: If you're looking to securely store files on your flash drive and unlock them without any installed software, WinPT is like a TrueCrypt you can take anywhere. TrueCrypt, one of our favourite apps for securing data on any system, requires administrative privileges to run on any system—a source of frustration for many commenters, and a non-starter when it comes to being truly portable. WinPT is a nice step-in solution as a portable, graphical front-end for GnuPGP, an open-source implementation of the Pretty Good Privacy encryption. Portable versions of both WinPT and GnuPGP are available from PortableApps.com, tweaked and ready to play nicely with each other right out of the box. All the standard encryption key tools are available, including a symmetric encryption option that does away with keyrings (but makes choosing strong passwords a must). The application is listed as an in-development beta on PortableApps.com, but in testing the product performs like a polished release. WinPT Portable is freeware, Windows only and requires portable GnuPGP.