SmartGit/Hg is a graphical user interface for Git and Mercurial which can work with SVN repositories. It supports cloning from common repository providers (e.g., GitHub, Assembla), assists Git newbies, and also offers the advanced, powerful Git features. It provides several tools to help create clean commits, for example by allowing the user to commit just parts of changes files and reordering and squashing unpushed commits. If you are using GitHub or GitHub Enterprise, SmartGit/Hg can work easily with pull requests (creation, resolving) and commit comments. SmartGit/Hg ships with a built-in SSH client, file comparer, and merge tool which are capable of syntax coloring for many languages.
A tool for editing version-control repository history, reposurgeon enables risky operations that version-control systems don't want to let you do, such as editing past comments and metadata and removing commits. It works with any version control system that can export and import git fast-import streams, including git, hg, bzr, CVS, and RCS. It can also read Subversion dump files directly, and can thus be used to script production of very high-quality conversions from Subversion to any supported DVCS.
deltasql is a tool to synchronize databases with source code, which helps to keep database evolution under control. While developing mid-sized or big applications, developers make changes to the data model that go along with changes to the source code. From time to time, branches of source code are done to stabilize the code that will go to production. A sort of data model branch is also needed. deltasql provides a simple way to collect all scripts that change the data model and means to handle data model branches. The deltasql server runs on Apache and is backed by MySQL.
OpenGrok is a fast and usable source code search and cross reference engine. It helps you search, cross-reference, and navigate your source tree. It can understand various program file formats and version control histories like Mercurial, Bazaar, Git, ClearCase, Perforce, SCCS, RCS, CVS, or Subversion. In other words, it lets you grok (profoundly understand) the source.
cvs-fast-export analyzes a collection of RCS files in a CVS repository (or outside of one) and, when possible, emits an equivalent history in the form of a fast-import stream. Not all possible histories can be rendered this way; the program tries to emit useful warnings when it can't. The program can also produce a visualization of the resulting commit DAG in the DOT format handled by the graphviz suite. The package also includes cvssync, a tool for mirroring masters from remote CVS hosts.