I'm currently at the SESUG conference with hundreds of SAS users. I've presented a few talks, and I've attended a few more. The presentation rooms can be large and dimly lit, and the projectors at these conference hotels are not always the brightest nor are they exactly "high def".
To spare my audience from further eye strain in my talks, I always use the ZoomIt tool when presenting a software demo. With a simple keystroke (Ctrl+1), the ZoomIt tool allows you to focus on a particular field, button, or line of code so that the audience can actually read it. (Ctrl+1 zooms in, Esc or Ctrl+1 again to unzoom. Keys are configurable.)
The Number One question that I hear when I complete my talk: "How are you zooming in like that?" (I'm not too proud to consider that this might be the most valuable information they take away from my presentation.) I'm happy to point people to ZoomIt, since I wish that more presenters used it while I'm in the audience.
ZoomIt also works for web-based presentations such as WebEx; just make sure that you share your entire display (instead of just a single application) when sharing content. If you share just a single application, the "magnified" content provided by ZoomIt won't be included in your transmission.
It's a lightweight tool: a single EXE file that you can copy and run from anywhere on your PC. There is nothing to "install", so no admin privileges are needed.