...there are times when you need it: creating a kernel dump "on demand". There has always been the option in Windows to crash the system (and create a memory dump) when you press (and hold) the Ctrl-key and then hit twice the Scroll-Lock key. The problem with it - it only worked with PS/2-keyboards, at least until recently. But not any more - now it is working with USB-keyboards as well. I am not sure if that feature appeared in Windows7 or Windows8 - so far I used it with Windows8.
Here is the command to enable the "Ctrl-ScrollLock-crashhandler" for PS/2-keyboards
reg add "HKLM\SYSTEM\CurrentControlSet\Services\i8042prt\Parameters" /v CrashOnCtrlScroll /t REG_DWORD /d 0x1
and here for USB-keyboards
reg add "HKLM\SYSTEM\CurrentControlSet\Services\kbdhid\Parameters" /v CrashOnCtrlScroll /t REG_DWORD /d 0x1
I learned this here. See also here.