Mercurial is a free, distributed source control management tool. It's lightweight and efficiently handles projects of any size with an easy and intuitive interface.
GitLab is a development collaboration tool and git DVCS frontend. It includes repository management features, code reviews, an issue tracker, activity feeds and wikis. GitLab provides fine-grained access control, user management, 5 permission levels and branch constraints, and can utilize LDAP/AD intranet authorization. Powered by Ruby on Rails it comes as open source package, and as commercial supported enterprise version.
FreeFileSync allows comparing and synchronizing local file folders. It's performant and without GUI complexity. It detects moved and renamed files, detect conflicts, can operate on locked files, understands symlinks, allows automatic syncing, copyies extended file permissions (NTFS), and it's cross-platform.
Darcs is a cross-platform version control system. It's similarly decentralized as git, mercurial or subversion but with a very different management approach. It focuses on changes rather than trees/snapshots. Which allows it to provide a freer way of working, and a much simpler CLI and a highly interactive user interface. It can work in an offline mode, provides local preparations, easy (non-)branching and merging, email patch sending, parallel development and builtin cherry-pickying from cha
Supervision is a GUI-centric version control system. It's implemented in Java and works cross-platform. Conceptually it uses "change sets" instead of focusing on files and tagging. Since version 2.0 it's multi-user and follows a client-server approach, the internal database is transactional, provides quick access to compact diffs, branching, merging, reports and full text searches.
DUB is a source file dependency resolver and package manager for the D programming language. It utilizes a simple JSON package description scheme, integrates with git for implicit release versioning, generates VisualD project files for MonoD, comes with support for DMD, GDC and LDC; and can utilize local directories as package source.