LYNKtec Stylus Pro
Some people find a stylus convenient to use with an iPad or even an iPhone. On the other hand, one usually thinks of using a finger on Apple's Magic Trackpad. However, a capacitive stylus designed for an iPad works beautifully on Apple's Magic Trackpad and is even more accurate.
Recently, I was having some pain in my right thumb, and I think it was because my Logitech mouse had a left button that was slightly too hard to click. That was putting some mild pressure on my thumb as I squeezed. Briefly, I thought about switching to a trackball, but after reading customer reviews and sizing up my own situation, I decided that a trackball wasn't the answer either. I looked for a different mouse with a lighter left button click. That would take the pressure off my thumb because I wouldn't have to grip so tightly.
I experimented with a lot of mice from my office, and, amazingly, the one I liked best was an old Apple Pro Mouse. I found it amazing that such an old mouse worked so well for me, but sometimes the future marches on with style and leaves ergonomics behind for some users.
I own and have used an Apple Magic Mouse, but I don't like the way a drifting forefinger can trigger a sideways scroll. Older mice restrict the scrolling to one dimension, and I like that.
Apple's Magic Trackpad. I've had an Apple Magic Trackpad for a long time, but it fell out of use for several reasons. First, it didn't have the resolution I wanted and, second, my finger would never seem to slide as easily as I wanted. Those two factors prevented fine cursor control when I edited my articles.
Apple's Magic Trackpad + Microfiber stylus = More magic
Then I had a brainstorm. Why not try one of those many styluses I'd been testing and reviewing for iPads? The ones that worked the best with Apple's trackpad surface were the ones with a microfiber tip, such as the TruGlide Pro Stylus or the older the TruGlide Stylus.
The smaller, 5 mm, microfiber tip of these styluses glides across the face of the trackpad much better than my bare finger in my experience and is more accurate. It's a solution worth trying for many who want to hold a stylus, like a pen, in a more natural, upright position.
The microfiber tip on these LYNKtec styluses is sturdy enough that you can push the trackpad down to click if you like that mode better than than the "tap to click" mode. (System Preferences -> Trackpad -> "Tap to click.") I may change my mind about that now that I'm using a stylus instead of my finger.
The only drawback to this technique is that if one is doing a lot of writing, one has to pick up the stylus after typing and then put it back down when done. That's not quite as convenient as a bigger mouse that's easy to locate and grab. Also, I've noticed that I need to push just a little harder on the trackpad surface than I do on the face of, say, an iPad. Not a lot.
If you're not happy with a your current mouse, and you're not convinced that a trackball is the answer, but you happen to have a an Apple Magic Trackpad laying around -- or have always wanted one -- give it another try. You may find that a microfiber stylus, or even one with a rubber nib, works better than anything you've tried so far.
Note: Related to all this, especially for trackpad users, check out Jeff Gamet's nifty video tip on how to enable OS X window scroll bars.