There are ways to get highlighting (reverse video, inverse video) in GNU Emacs 18.58, but either they require patching the C code of Emacs and rebuilding, or they are slow and the highlighting disappears if you scroll or redraw the screen and it can not follow the point. Howard Gayle's patches for 8-bit output appear to allow highlighting (see question ^8-bit-output). Another patch for highlighting is by Kenichi Handa <handa@etl.go.jp>. There is a patch for use with X by Andy Norman <ange@hplb.hpl.hp.com> (and modified for 18.57 by Matthieu Herrb <matthieu@laas.fr>), which is available for FTP:
/laas.laas.fr:pub/emacs/patch-X11-18.5{5,7}
You can highlight regions in a variety of ways in Epoch and Lucid Emacs. GNU Emacs 19 may not be able to just temporarily highlight a region.
Similar comments apply to displaying text in different fonts, except that it is even harder.