That works in the linux command line, and in this text field on linux:
Similar methods available for windows and mac, I imagine.
Typing the more unusual characters has always been way easier on Macs. (Literally since Macs were invented.)
That used to be the case, but I find the Compose key in X is awesome: as others have noted, Compose / = → ≠ (and → is Compose - >)
Certainly longer than typing !=, but far easier than looking up hex values.