I recently came across LazyMouse, a little Preference Pane app that snaps the mouse pointer to the default button in dialogs when they appear. The idea here is that you’re most likely to click the default button, so why not have the mouse cursor move there automatically and save the wrist-ache?
To be honest, I’m surprised this isn’t a standard option on the Mac; I seem to remember this being an option in Windows since way back in the mid-nineties. To add insult to injury (sorry – bad pun), you have to pay $10 for this app. And you can usually just hit the Return key to activate the default button (or Esc to back out of a dialog) anyway.
That said, for what it does, LazyMouse is nicely done. You can choose to snap the mouse cursor to the default button (such as Open) or the alternate button (such as Cancel). You can also have the cursor snap back to where it was before the dialog appeared – a very useful feature (though unfortunately it doesn’t work if you move the mouse at all when the dialog is open). LazyMouse also comes with a nice, easy-to-read manual.
If you do a lot of mouse-work and have problems with RSI or other hand/wrist injuries then LazyMouse is certainly worth a look. It’s shareware too, so you can try it out before you buy.