Yes, I still have my book "Object Oriented Programming in the BETA Programming Language" by Madsen/Møller-Pedersen/Nygaard with a price tag of 80 DM in 1997 (> 40 EUR now) (I now live in Berlin)
No, but the Racket OO system is based on BETA's implementation of OO, and Racket has some actual users. There's definitely some interesting ideas there.
For example, `inner` being the opposite of super (e.g. call the subclasses implementation of this method). Some others, but I'm not sure I remember them (Augmentation?).
Self, JavaScript, CLOS, Go, BETA, Clojure Protocols, Type Classes, COM and probably quite a few others.
What most mainstream developers know, is not the only way.