If you deal with a lot of other businesses, it's really beneficial to take the time to visit them. This may not always be possible if there are geographical constraints, but how often have you been dealing with a good local customer for years, yet you have no idea what their business premises look like or what they actually do?
Take some time to drop by and see where it is that your customers spend their day. This may give you an insight into them and the way they think and work. It shows that you are taking an interest in them. This interest needs to be genuine if it is to benefit both your customer's business and your own.