VeraCrypt is an open-source utility used for on-the-fly encryption (OTFE). It can create a virtual encrypted disk within a file or encrypt a partition.

Cryptonite brings EncFS and TrueCrypt to Android. You can browse, export and open EncFS-encrypted directories and files on your Dropbox and on your phone.

EncFS is a Free (LGPL) FUSE-based cryptographic filesystem. It transparently encrypts files, using an arbitrary directory as storage for the encrypted files.