dbslide is a collection of DSSSL stylesheets, cascading stylesheets, and some helper files to generate presentations from DocBook documents in various formats:
The HTML version can be presented in any web browser. If the browser supports CSS, the presentation will actually look good: the font sizes are suitable for projecting it in front of an audience or to run a presentation on the computer screen for people that don't sit directly in front of the screen, as e.g. in booths. If the browser also supports JavaScript or JScript, you can also run the presentation with your mouse or the keyboard.
You can also generate printed output which is suitable for slides or overheads. The font sizes are again larger than usual.
You can create plain printed output which makes nice handouts: they do not look as ugly as the usual copies of the overheads.
With the help of the standard SGML feature of marked sections you can also create a speaker's printout, including additional comments.
You will notice that this is a completely different approach as compared to e.g. MS PowerPoint presentations. Apparently the main point here is not the full control over the exact layout of the output. If you need that, you're better off with some graphical presentation software. The main objectives of the dbslide approach are:
Use a platform-independent and software-independent source file (SGML) with an "industry-standard" document type definition (the DocBook DTD)
Use platform-independent output formats for the printed versions (e.g. PostScript, PDF) and for the presentation (HTML)
dbslide is very well suited for mainly text-oriented presentations. Although you can basically use all DocBook elements including those for equations, graphics and the like, it may need some fiddling to get those elements displayed the way you want it. All in all, think of dbslide as something as the slide class is in LaTeX.