When I want to find a \"Big\" Web service (WS-*/WSDL based) of required functionality I can simply google for \".... filetype:wsdl\" because Google indexes also WSDL definit
There is a convention (recommended in REST API Design Handbook for example) that you expose a /api endpoint at the root of your service. This returns an XML or JSON response containing the "child" resources that your service supports e.g. /api/products