Windows only: My Lockbox isn't a full-featured encryption solution like TrueCrypt, but it is an easy and free way to hide a folder from all but the most technically savvy (and extremely prying) eyes. Install the program, choose a folder you want to hide (or let it create a "My Lockbox" in your My Documents folder) and then run the program to unlock and add files to it. Shutting down the program or even booting into safe mode won't reveal your folder, unlike many other "hiding" utilities, and even looking at folder sizes won't reveal your data. Somebody with a recovery disk and knowledge that you're hiding something might breach your data, but for most people's needs, My Lockbox gets the (secret) job done. My Lockbox is a free download for Windows 2000 and later.