Mouse.

[Hitman]

Shhh hitman,why u need more DPI? My MX have 1800,and i use only 900,and work fine,so i don't understand some mouse like Razer Imperator,he have 5600 DPI,damm...1000 DPI in SAMP/CS is w0w great...

I use around 1400-2000 dpi, depending on what application im running.

And, dpi is not just about speed, but also about accuracy, so a 4000dpi mouse can make sense, if you reduce the mouse speed in the windows settings but also increase the dpi of your mouse, the "speed" will remain the same but its more accurate. Same for the refreshing rate (100Hz, 500Hz, 1000Hz).

People will always say "why would anybody need that?". Yes, yes. Some guy even said that "640KB ought to be enough for anybody".