Services
If you have any extra services you want to sell, you can set them up here. A golf round, theatre tickets, transfer to/from the airport, insurance and so on. The possibillities are endless.
If you have items that don't need any inventory, you can add them here too. Insurance for instance can be added here.
You can link some services to specific hotels, so that when your customers are booking a hotel from your site, you can offer them specific services only offered on that hotel. That way you can even have different price structures for transfers.
You can also set the service item only to be visible when your customer is arriving at his destination or departing from the destination.