The first one that really comes to mind is the Western Lariat. You know which one I'm talking about Lariat. Stan Hansen used it so well, and JBL did as well. Now with JBL being gone and the lariat being somewhat of a standard move, I can't help but think that it would be awesome to actually see someone use it as an high impact finisher once again. This is one of the primary reasons why I miss JBL. Awesome wrestler, with an awesome yes simple finisher.
Also, I wouldn't mind seeing some suplexes being brought back into wrestling as a way of being a finisher. Not necessarily all those fancy northern light suplexes, german suplexes etc. that some people use to seem more technical. No, something simple like a vertical suplex (I'm sure that has been used as a finisher at one point or another). Now I know it's gonna be hard to implement a suplex into a finishing maneuver once again, because quite frankly it's such a regular move now. But so was the sleeper, and Dolph has given that a decent amount of relevance again.