Projection. Bring your own laptop with PowerPoint or Keynote ready to go (maybe have your presentation on a thumb-drive as well). The room has a ceiling-mounted LCD projector with connections for two laptops, so initial setup is relatively painless. It's still a good idea, though, to come a bit early in case there are glitches. If you're using a Macintosh, make sure you have an adapter for the video connection (or alert Pete Wishnok, Aran Parillo, or Alexis Runstadler).
Once connected, the laptops can remain turned on and awake; the second speaker, while being introduced, can simply go to the control panel and select PC2 or PC1 (whichever wasn't used for the first speaker).
Powerpoints or Keynotes. Approximately one slide per minute. Each slide should have as little information as possible (not a misprint!), in large type. (In one website about Really Bad PowerPoint, there's a rule that no slide should have more than 6 words; a less extreme rule is: no more than 6 lines and no more than 6 words per line.) Avoid clutter and too many colors. Avoid red lettering on dark backgrounds and yellow lettering on light backrounds.
If you have very large tables of data, divide them up into smaller units or make smaller tables with extracted key or representative data. Actual data is important and informative, but it is not usually necessary to show all the data from every experiment that you've carried out.
If you find yourself apologizing for your slides, or saying things like 'You can ignore most of this slide and focus only on this row', then you should redo the slides.
Click here for a pdf file with some bad/good examples.