The date operators from: to: I think have been unsupported for a while and replaced with a dropdown in the UI
filetype: is a fave and has been working for as long as I can remember
AROUND(number) is pretty useful too although I find that might be a bit buggy sometimes
There is a good list here https://www.exploit-db.com/google-hacking-database showing how dorks can be used for pentesting and/or generally finding insecure stuff