The CvsGui project is providing several high-end interface clients (WinCvs, MacCvs, gCvs) written in C++ using popular frameworks (MFC, PowerPlant, GTK+) with a scripting support via Python or TCL.
Yet Another Diff Tool
YaDT - Yet another Diff Tool. It is another front-end for diff and in earlier versions diff3 utility. With YaDT you can compare and merge 2 and/or 3 files. YaDT is written on Tcl/Tk and wrapped in a single executable file with the help of sdx and tclkit. diff and cvs utilities are embedded inside YaDT. Also, YaDT supports Git and Mercurial repositories, but git and hg are not embedded inside YaDT, you should have git/hg executable in your path environment.
CTMBSD is an attempt to make a portable version of original CTM (Cvs Through eMail) obtained from FreeBSD (tm).
tclDBRCS is a database oriented revision control system which is fully database oriented and features full project/tag/branch support. It also supports optional encryption of file content. Can be used inside other applications as a package.