In April 2008 the State of New York inserted an item in the state budget asserting sales tax jurisdiction over Amazon.com sales to residents of New York, based on the existence of affiliate links from New York–based websites to Amazon. The state asserts that even one such affiliate constitutes Amazon having a business presence in the state, and is sufficient to allow New York to tax all Amazon sales to state residents. Amazon challenged the amendment and lost at the trial level in January 2009. The case is currently making its way through the New York appeals courts.
It's beneficial for the company because it receives both advertising and sales leads that it wouldn't necessarily be able to access otherwise. It's also beneficial for you and their other affiliate publishers, who are able to make money from sales without actually having to get involved in handling the transaction. Since all you're doing is essentially connecting people with products, affiliate marketing can be one of the most time- and cost-effective methods to make money online. (See also: 5 Ways to Make Passive Income Online)
You should also make sure you aren't competing with your own affiliates for eyeballs. Any marketing channels you're using, such as search engines, content sites or e-mail lists, should be off limits to your affiliates. Put marketing restrictions into your affiliate agreement and notify partners immediately. It's your program--you set the rules. Or, if you prefer, you can let your affiliates run the majority of your internet marketing.
Affiliate marketing is often touted as a "get rich quick scheme" by shady sites offering pyramid schemes that promise quick cash for little effort. Make no mistake—successful affiliate marketers like Pat Flynn of Smart Passive Income put in a lot of effort toward building an audience and creating quality content that will bring in sustainable passive income. Expect to do a lot of legwork up front—but if you play your cards right, you can build a solid source of revenue over time.