SOAP has been largely superseded by REST on the public Internet - as you have noted in your question and has been alluded to in comments.
There are still large users in the Intranet context, companies with an installed base of SOAP, Service Bus, and other concepts that you may well come across if you end up working at one of them. (There are still CORBA users out there also!) When you control both ends of the application, you may have less reason to be flexible using REST.
So if you are looking for useful public implementations you are mostly out of luck.
That said: do create your own services and try them out on your own. Define a service and implement it. Create a client in a different language. Create another client in a third language.
If you are looking for an educational experience, this will lead you down some of the same paths that has lead to REST use in wide-scale disparate systems (and may also shed light on why the public/private has split the way it has)
Good Luck