A pen is a fantastic way to get inexpensive advertising, which can lead to new customers. Pens have nine lives, meaning they get passed around like crazy. Don't believe me? Go look at your pens, how many are from the bank? From various stores? From random places? Get some pens printed with your company name, logo, website, etc. on it. Pass them out at your store, at fairs, etc. Leave them all over the place. They are going to advertise your name, and contact info every time someone uses them.
The cost of a pen can be very little. Pens can be purchased in bulk with custom printing, and the cost for a whole set is likely to be covered if you get just one customer out of it. So, the potential for customers is high, and the cost is low, making it a great way to advertise your business. In addition, you can use different logos, phrases, etc. on the pens to promote all or some of your products.
Pens are lso multi-purpose. You can carry them in your store for customers to use to sign credit card slips, and cross things off shopping lists, etc. enforcing your brand. Send them home with them, and they will use them and have a constant reminder of your brand. The more familiar they are with it, the more likely they are to buy from you.
This holds true for potential customers. If they get one of your pens, they are going to constantly see your advertising, and if they need what you offer, you will be the first person they go to. For example, if you are a plumber, then make pens, and distribute them like crazy. Then, if their toilet ever gets clogged, or their drain is plugged up, they will know who to call.