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.
ded, the directory editor, allows you to navigate multiple file lists or a directory tree, viewing or changing file attributes rapidly. In addition to conventional file information, it operates on files' RCS or SCCS archives, making it useful for source control as well as system administration. It is curses-based.
eacc is a bash script that allows a group of people to share an encrypted, revision controlled file on a shared filesystem. Rather than store an encrypted file in RCS, eacc encrypts the RCS file and handles the decryption, check-out, check-in, and encryption steps automatically. The repository is encrypted using GPG's multi-recipient support, which allows each member of the group to use their own unique password. A typical use case would be to securely store sensitive information, such as password lists or account information, that is shared by a team.
TkCVS is a cross-platform, Tcl/Tk-based GUI for the CVS and Subversion configuration management systems. It displays the status of the files in the current working directory, and provides buttons and menus to execute CVS, Subversion, or RCS commands on the selected files. The Log Browser displays a branch diagram of the revision history. The Module Browser extends CVS with facilities for a user-friendly listing of modules in the repository. TkDiff is included for browsing and merging your changes.
Chora is built upon the Horde Application Framework and provides a read-only browser interface to any number of version control repositories. Advanced features include a visual branch view of the repository's history, pretty-printed output, annotation, patchsets and basic statistics.