Use a two-finger pinch on a trackpad to zoom the text in TextEdit documents. Pinch your fingers apart to zoom in, and pinch them together to zoom out.
[kirkmc adds: This works zooming in and out with TextEdit. I expected it to work in other apps, and it does in Preview. However, it only works zooming in with Safari; if you pinch together, you see the currently open tabs, as explained in this hint.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20120812195052928