I find Scroll Lock necessary to switch between analogue monitors using a Belkin 2 port KVM switch. (Never found any other use for it though.) You double click on Scroll lock then click on No1 or No2 monitor--works very well too.
There are several keys on my latest keyboard that I never use.As a one finger typist,I must look at the keys as I type & as its all black with white lettering I need plenty of light to use it at night.The thing I am really annoyed about is I have a keyboard from my first ever PC,its beige in colour and despite many years usage,all the letters are still visible.This latest keyboard is under 4 months old,and has lost so many of the letters off the keys,I have to "proof-read" everything.I tried tipex pens,that worked for a single evening.I have now sat with a needle and lighter,heating the needle and carefully burnt the letters into the key tops then painted over with tipex which at least enables me to see what key it is I'm pressing and wont wear off.(or if it does,it'll be time for a new keyboard as I'll probably be poking my finger into the innards)