DiskCryptor - fully open solution to encrypt all partitions, including system. The program is a replacement for proprietary DriveCrypt Plus pack and PGP WDE.
Product is not bad at all. It supports single platform (Windows only) and has no portable version. The documentation is weak at the wiki-website level but hey, its a free product. the big plus is that it is mature, it is still around after Truecrypt ended its development lifecycle. A quick review of the source indicates that it is quite well written although I have to say that we are not that well qualified to properly assess / be authoritative about optimizing cryptographic algorithms for x86 & x64 cores. Out of the box, the app natively supports AES-TwoFish-Serpent and combinations thereof, and subjectively speaking, it appears to be quite fast even with a 2 or 3 algorithm cascade on dinky 2 core and 4 core processors, but does take a bit of time to encrypt larger HDDs, especially when theres less processing horsepower / memory available.. Definitely no complaints for what's bundled in and the bootloader options are indeed versatile, and especially for what you have to pay (as in free :D). Love to see ARM support and a few more features if the foundation can see to expanding the product. If you don't have to worry about IRL Adversaries / Quantum Computer Decryption, IMO this will more than serve your crypto needs. This is our migration path for all the legacy Truecrypt Windows based installations. Does ours quite well so thank you!
Easy to use, boot loader highly configurable and many encryption algorithms to choose from, including chaining of algorithms, I found it very quick to encrypt my hard disk, I love this product.