I think yes there are some that provide you with a landing page or you can use the same template as they do on their homepage, but I don't know any of these. However, it's really easy to start your own website. You can use e.g. Wordpress to build your site. There are also many good free themes.
Some industries provide you with full store fronts, you will need to come up with the domain though. Hosting can also become an issue, depends what you are selling.
good affiliate programs will give you landing pages, today the competition is great so you can always ask your affiliate manager to help you
What you are looking for is typically called a White Label Affiliate Site. So you could try Googling that. The down side is the same site may be used by hundreds of affiliates, therefore would be duplicate content and may not get any good rankings by the search engines. So it's not a good option if you are starting as a newbie and want to get free search engine traffic. The landing pages people above are talking about are not sites, but single sales pages, usually offered by some CPA networks not affiliate networks. They are also mainly used for PPC marketing which is a pretty risky and expensive way to get started if you don't know what you are doing. Let me know if after reading this you want some other ideas.
Hi they are many affililate companies that will provide free sales page website ive just also started a affiliate program which i will list on here after my 7 days and of course 10 post. i will pm you the details about it and you get paid every month via paypal also ive started the affilate program through paydotcom so you will get paid on time everytime. Also i provide a sales page too , you also get 60% per sale or you could just google white label affiliate site