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.
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.