hp2xx is a versatile tool to convert vector-oriented graphics data given in Hewlett-Packard's HP-GL (a.k.a. HPGL) plotter language into a variety of popular both vector- and raster-oriented graphics formats. The various supported output formats include Encapsulated PostScript (EPS), PCX, IMG, and several formats intended to facilitate the generation of graphics within TeX documents. In addition, hp2xx output is printable on the HP Laserjet/Deskjet printer series, and it may be used as a HP-GL previewer on many platforms, e.g. X11 and DOS (VGA).
Xpdf is a viewer for Portable Document Format (PDF) files. (These are also sometimes also called 'Acrobat' files, from the name of Adobe's PDF software.) The Xpdf project also includes a PDF text extractor, PDF-to-PostScript converter, and various other utilities. It runs under the X Window System on UNIX, VMS, and OS/2. The non-X components (pdftops, pdftotext, etc.) also run on Win32 systems, and should run on pretty much any system with a decent C++ compiler. Xpdf is designed to be small and efficient. It can use Type 1 and TrueType fonts.
dxf allows you to easily open and edit DXF (Drawing eXchange Format) files. You can export them to various image formats (BMP, PNG, GIF, etc.) or print files. Many entites are supported (lines, arcs, circles, polylines, text, trace, and solids), as well as all colors including BYLAYER. Background color can be changed from black to white. LTYPE (linetypes) are partially supported.