You probably take your mouse for granted, but they've come a long way.
Here are a few notable mice through history:
First up, the first mouse ever:



Invented by Douglas Engelbart and demonstrated at the Fall Joint Computer Expo in San Francisco on December 9, 1968. Here is the patent design (click to enlarge):

Next, a Soviet design -- yeah, they had their own little computer industry going for a while too:

Not bad considering we're talking about the Soviet Union -- in the 80s -- here. Notice the construction. If these mice were anything like some other Soviet products, they were probably designed to survive a hell of a beating.
And finally, the first Microsoft mouse:

I thought it was pretty interesting how similar it is to the Soviet mouse. Insert your own joke here.