Worldwide classified advertising is a great way to promote your products and services, especially if they are accebible to the whole world, via the computer, or telephone etc. There are many people who require services from around thw world, for example shopping websites, online tutors and freelancers.
The great thing about being able to advertise to the world is that you dont have to limit your services to one specific country. the whole world is at your feet - well, computer screen! Let the world know you have just the right skills for a job, or that perfect vintage dress, or a much needed travel packedge.
You can advertise many things, as well as what is mentioned already. If you have affiliate services that you need to advertise, then why not advertise them to thw world? You can sell an E-Book, a service or absolutly anything that can be posted, used or accessed over the internet.