One surprise you can give customers is a referral to your competition. For example

Building a Business Reputation You Can Be Proud Of

The excitement you feel once your business is up and running is hard to put into words, but that excitement can turn into fear if the sales don start coming in soon after you launch. However, you can avoid that fear of early failure by building a business reputation that will lead to sales and quick success. Here how:
Keep Your Word
When you create your policies on returns, guarantees, shipping and etc., make sure you can honor everything you promise. For instance, let say you tell your customers they can return a product for any reason within 30 days after they receive it and get a full refund. Now, a customer decides he not satisfied with the product he ordered and sends it back within the 30-day time limit, how do you handle the situation? You honor his request by sending the promised refund, of course. If you feel you later regret that policy, it time to change it before you have to honor it. To maintain a customer-friendly policy, you could charge a low restocking fee for items that aren defective. I think you see where this is going, right?
Admit When You Wrong
Everyone makes mistakes, and they can be embarrassing, but you earn more respect by admitting your mistakes. Don just fess up, though, do your best to correct the problem, especially if the mistake involves a customer.
Show You Care
If you know your customers birthdays, send them a greeting card with a free gift. It doesn just have to be birthdays either, you can also send a sympathy card if you know they lost a loved one. Or if you haven heard from your customer in quite some time, send him/her a thinking of you card with a special offer enclosed.
No matter what greeting card or gift you send, you be surprised how much they appreciate and remember your thoughtfulness.
Go Above and Beyond What Expected of You
Customers expect you to answer their questions and assist them with any problems that may occur with their orders, but what makes them happier is when you give them something unexpected.
One surprise you can give customers is a referral to your competition. For example, maybe the customer is searching for a product that you don have and can get but you know one of your competitors has the product. Yes, you in competition with the business, but you stand out more by letting your customer know he/she can order the product from your competitor. By doing this, your customer will remember you and probably return later to purchase something they know you do have. In addition, they may let their friends know how you went out of your way to help them.
If you follow this advice to build a business reputation you be proud of, you can bet most (or all) your customers will tell their friends, family and colleagues about you.