Want a new pair of jeans at the Gap? You can get paid to go to the Gap, buy a pair of jeans, and then write a brief synopsis which explains your overall shopping experience and level of satisfaction. You'll get paid to shop and whatever you buy will be free! It's like shopping - with an expense account.
Paid-to-Shop has also been called "Mystery Shopping", because you're actually doing some covert reconnaissance for a particular company. Either a business will hire you to evaluate their competition, or a business will contract you to evaluate their own products and services to ensure quality control. It's fun, and even better - It Pays!