There are innumerable reasons you might require a custom banner or signal, and also you never know when you will. Here are four affairs that you might:
A Grand-Opening: Encourage it well, and you want to promote it, in the event that you're opening a store or shop of any kind. The primary couple of months for almost any company are critical, along with just the impetus you should get through them can be generated by a great opening.
Going Out-of-Business Sale: Conversely, you need to advertise only as much in case you are having a going out-of-business sale. This can be your last opportunity to earn a profit in your investment, therefore bust-out the flags and banners and window images to let people learn about your going out of business sale. Again, advertise you can -- you need as many customers as possible only at that final deal.
Special In-Store Promotions: Depending on what type of company you run, attempt to get a celebrity -- otherwise or neighborhood -- to do a meet-and-greet or signing of some sort. Say you have a bookstore -- get an author with a novel that is new out to do a studying. Or, if you operate at a sports goods store, consider getting a well known athlete in the area to sign autographs for an afternoon.
Any Continuing Promotions: You may have events or special prices once a week, once per month, perhaps even once a year. Regardless, if there's any sort of repetition to an event or sale, have a custom banner or sign made up, something like, "Huge Blow-out Sale, This Thursday!" (assuming you consistently have it on a Thursday). Or, you might have a signal made up having a spot that is clean so you can tape on the day and date.
Regardless of the occasion, make sure to apply any signage that is physical together with the Internet you utilize. That is what it is there for -- to spread the phrase about, well, everything. Twitter, use Fb, MySpace, a Linked In, everything and anything you can. Set up an Yelp accounts so folks can afterwards write critiques of anything you're planning, and be sure you're on FourSquare so folks can "check in" when they visit your shop. Signs and banners are ideal for receiving the initial word out there, but you require follow up advice that people can save on their computers or telephones.