With the exception of Apple's now-defunct single-button mouse - beloved by Luddite Mac fans everywhere - input devices don't get much simpler than the Kensington Ci73 Wired Mouse.
The Kensington Ci73 Wired Mouse has two buttons and a scrollwheel. That's it, folks - you can go home now.
You can switch the Kensington Ci73 Wired Mouse's right-click/left-click behaviour and adjust its tracking, scrolling, and double-clicking speed, but that's all. You can't, for example, assign an alternate behaviour to the scrollwheel button.
The Kensington Ci73 Wired Mouse's USB cable is fully five feet long, which is more than ample for reaching any USB port regardless of your favoured hand. Unfortunately, if you use a USB port on your keyboard, the cord is also long enough to get in your way.
Although it's a featherweight at around 90g, the Kensington Ci73 Wired Mouse carries much of its weight in its rear, giving it a tendency to pivot a bit when moved laterally. Also annoying is its small, somewhat tough-to-roll scroll wheel - our scrolling finger would sometime slide across it if I didn't push down hard enough.
Quibbles aside, the Kensington Ci73 Wired Mouse's tracking capabilities are quite good; we had no problem whatsoever doing minute pixel-by-pixel work in Photoshop and Dreamweaver.
We also enjoyed the comfortable ribbed-rubber bumper enclosing the outside of the Kensington Ci73 Wired Mouse's shiny black plastic body. Ergonomically, we found its low profile to be a bit too low, but you may find the Ci73 to be perfectly comfortable.