Overhead sheets / P*Point

What are your ideas about projection materials? In earlier days, I
used overhead sheets, but nowadays I present the sheets using
Ghostview or Acrobat Reader, using a beamer.
One advantage of the beamer is that I can instantly switch to a
terminal or emacs window to show additional things.
Disadvantage is that customers sometimes have very bad beamers (I
teach on-site).

Currently, I'm considering to migrate to the Portable Presenter, so I
can show the sheets using Perl-only tools.

-- Johan