:You don't need any special package (like prosper or seminar in LaTeX) to make a presentation. In contrast to LaTeX, changing the document size, changing colors, adding hyperlinks, ... appears to be extremely simple in ConTeXt. See [[Presentations]] for more specific topics.
=== <code>\setupindenting[medium]</code> doesn't work? ===
:This does work, but the effect is not what you expect. Without <code>yes</code>, you have now set up the default size, but you have not turned paragraph indenting on. You have to execute <code>\setupindenting[yes]</code> before it starts actually indenting your paragraphs.