Have you ever noticed that when a dialog box comes up, you have to move the mouse from wherever it might be all the way over to the dialog? Snap-To automates this little wrist jerk, moving the cursor automatically to its most likely destination -- the default button.
Many sufferers of repetitive stress injuries (RSI) and carpal tunnel syndrome report that Snap-To has worked wonders for them by significantly reducing the distance they have to move the mouse. Even if you're fortunate enough not to have such afflictions, Snap-To can provide you with noticeable speed improvements when using your Mac, and keep your carpal tunnel that much happier.
Snap-To also has a couple of extra features, such as the ability to automatically disable itself in Open and Save dialog boxes, where you're more likely to want to select a file or type a name first. Snap-To can also smoothly "glide" the cursor over to the default button instead of abruptly snapping it there, or put the cursor back to where it was before the dialog box popped up.