Meld is a visual diff and merge tool. It integrates with most version control systems. The diff viewer lets you edit files in place (diffs update dynamically), and a middle column shows detailed changes and allows merges. The margins show location of changes for easy browsing, and it also features a tabbed interface that allows you to open many diffs at once.
Hgfs is a read-only filesystem interface to Mercurial repositories. The interface gives access to the commit message, manifest, and files of each revision, and to .tgz's of each revision (the .tgz's are generated as they are read). The filesystem is a front-end for the Mercurial library that comes with it. All code is written in Limbo, for Inferno.
CVS, GIT, and Mercurial as well as other well-known version control systems cannot version directories. In other words, you cannot add empty directories. A "workaround" for this issue is to use placeholder files that are placed into empty directories. These placeholder files can then be committed into the repository and will make sure that, upon checkout, the directory tree is entirely reconstructed. The problem with using placeholder files is that you need to create them, and need to delete them if they are not necessary anymore (because sub-directories or real files were added). With big source trees, managing these placeholder files can be cumbersome and error prone. MarkEmptyDirs can manage the creation/deletion of such placeholder files automatically. It creates placeholder files in all empty "leaf" directories. If later on new files or directories are put into such directories, the placeholder files are not necessary anymore, and are removed automatically.
RhodeCode (formerly hg-app) is a Pylons framework based Mercurial repository browser/management with a built-in push/pull server and full text search. It works on http/https, has built-in permission/authentication (+ldap) features. It's similar to github or bitbucket, but it's supposed to run as a standalone hosted application and it focuses more on restricted access to repositories. It's powered by a VCS library that can handle many various version control systems.
Mercurial HeadQuarter is a Web service for managing Mercurial repositories. It allows the user to define contact names, define project descriptions, set up access (read and write), set which types of archives are allowed, define encoding charsets, hide/unhide projects, set the presentation style, and redirect access and error logs to files.
owl2vcs is a set of tools designed to facilitate version control of OWL 2 ontologies using version control systems. It contains a commandline diff tool for OWL 2 ontologies integrated with Git and Mercurial. It detects axioms additions and removals, imports' additions and removals, ontology annotations' additions and removals, prefix additions, removals, modifications, and renames, ontology IRI and version IRI changes, and ontology format changes. It supports RDF/XML, OWL/XML, OWL Functional Syntax, Manchester OWL Syntax, and Turtle. It provides a changeset serializer and parser, two formats of changes, compact (like OWL Functional Syntax) and indented (the same, but more readable, using indents instead of parentheses), and four formats of IRIs: Simple, QName, Full, and Label.