Physics cards, "gaming" network cards. No matter how low you rate an infinitely useless product, it's not low enough, so they are overrated by default - you can't beat that.
I think "gaming" mice are, as a rule, worth it. I recommend low-end gaming mice for nongamers, actually. They are normal mice, but better - more accurate, better ergonomics. For the average user, keyboard, mouse and screen are much more important than a few megahertz or gigabits here and there.
I don't understand the little "pad" gaming keyboards. Are they actually good for something? (Never even seen one in person.)
Also, anyone know how the Tarantula, G15 and such compare to premium keyboards from Unicomp, Matias, PFU etc. that are *not* marketed for gamers?
To the OP. Even a lowly mouse pad is part of interior decoration. Many people will buy a $1000 desk that is functionally equivalent to a $20 desk, just because it looks good. In comparison, a beautiful $50 mousepad vs an ugly $20 one is a steal. It probably has a functional benefit to boot.