You can define multiple connections to external data sources for the purpose of synchronizing asset details without having to use the API. There is also the option to do an WMI based discovery of your network.
You can use the API to programatically read Asset information from WHD. You can also use the API to submit tickets; i've seen people make a SharePoint page with some web form entries where end-users select/enter data and then the API is used to create the tickets directly.
