Class::Date provides a date datatype for Perl. You can create new Class::Date objects with a constructor from different scalar formats, array refs, and hash refs, and then you can easily manipulate it by the builtin "+" and "-" operators (e.g., $date=date([2001,03,15])+'3Y 1s'). Relative date types also available.
VTAGS is a command line application that will generate a VI(M) compatible tags file for VHDL source files. This application will read standard VHDL'87 files. It should also parse later VHDL, but it only takes account of the basic parts of the language. It will group items that it finds by architecture, procedure, function, or package. It does this by adding extra information to the extension field of the tags file.
GSview is a graphical interface for Ghostscript, an interpreter for the PostScript page description language used by laser printers. For documents following the Adobe PostScript Document Structuring Conventions, it allows selected pages to be viewed or printed. GSview requires Ghostscript 7 or later.
Elvis is a clone of vi/ex, the standard UNIX editor. Elvis supports nearly all of the vi/ex commands, in both visual mode and ex mode. Elvis adds support for multiple files, multiple windows, a variety of display modes including "hex" and "html", on-line help, WYSIWYG printing, and other miscellaneous extensions.
XCircuit is a UNIX/X11 program for drawing publishable-quality electrical circuit schematic diagrams and related figures, and producing circuit netlists through schematic capture. XCircuit regards circuits as inherently hierarchical, and writes both hierarchical PostScript output and hierarchical SPICE netlists. Circuit components are saved in and retrieved from libraries which are fully editable. XCircuit does not separate artistic expression from circuit drawing; it maintains flexiblity in style without compromising the power of schematic capture.
Yabasic implements the most common and simple elements of the basic language. It comes with goto/gosub, with various loops, with user defined subroutines and libraries. Yabasic does monochrome line graphics and printing. Yabasic runs under Unix and Windows, it is small (around 200KB) and free.