FreeOTFE is a file / volume encryption tool. You can use it to create encrypted file systems (disks), or container files to securely store confidential information. FreeOTFE can read / write volumes and container files created using DM-crypt in Linux. Encrypted volumes or containers created in FreeOTFE can be read in Linux too.
Get FreeOTFE here http://www.freeotfe.org. FreeOTFE is also available for PDAs and Windows CE smartphones.