In addition to stl2pov, I’ve now written a program that writes a shaded projection of the STL file (along the z-axis) as a PostScript file. It supports arbitrary rotations of the STL file around x-, y- or z-axis and automatically centers the object in the view, so you can easily create views of the object from all sides. Unsurprisingly this is called stl2ps. PostScript can be easily converted to a PDF file with e.g. ghostscript (or its pdfcreator front-end for Windoze). Creating a PostScript file and then viewing it with an appropriate viewer is generally _much_ faster than running it through POV-ray!
To the right is a picture of the metatron STL file, which has been rendered as a PostScript file by stl2ps. (The PostScript file has been converted to a PNG file by ImageMagick for inclusion on this webpage.)
Creating this extra program was not that hard, because I implemented the STL file reader as a stand-alone Python module. Basically it reads the STL file and then creates an STL object that contains a list of facets (triangles). This object is also an iterator, so it it easy to step through all the facets. Since this code is BSD-licensed, you can easily re-use it in your projects.