Here at VSLive! 2006 San Francisco, I've been sitting through a lot of presentations. Unfortunately, I've spent a disproportionate amount of that time staring at tiny, unreadable 12 and 10 point IDE text.
In OS X, it’s as simple as enabling the Zoom option under the Universal Access system preference, and then typing Command-Option-Plus to zoom in and Command-Option-Minus to zoom out.