BlackHole is an data de-duplicating network block device that also supports mirroring, snapshots, and support for multiple LUNs using the same data store. It is filesystem agnostic and has been tested with ext2/3/4, NTFS, ReiserFS, and the Oracle Cluster File System (OCFS2). It supports encryption, compression, and multiple storage backends. The hashing scheme used is user configurable. The program exports an NBD device which can be mounted in Linux and GNU/Hurd.
Self-Adjusting Top Tree Implementation maintains a forest that changes over time through edge insertions and deletions. This implementation focuses on the simplified Top Tree interface, which allows you to solve a number of interesting graph problems like finding common ancestors, the heaviest edge, maintaining the diameter, center, or median and other (mostly network flow) problems. Using Top Tree interfaces, all outline problems can be solved in a clean declarative way. This implementation uses adapting ST-trees as the underlying data structure, achieving O(log n) time per expose(v,w) operation. There is also a demo that shows an easy way to integrate the toptree library and the host application.