Calendars and clocks
One thing Flash does by default is look at the date and time in the user's computer. What makes this important is that brands can leverage this information to create custom messaging.
A great example of this is a banner campaign launched not so long ago by Special K. The campaign was "The Special K Challenge." What's the challenge? For women to lose weight by eating more Special K.
The challenge on the agency side was to find a way where the brand can remind the audience to eat Special K during each daypart. But how do you do this effectively without breaking the bank on the media buy?
This is where Flash comes in handy. Instead of having to re-engineer the buy, the same single Flash movie that was used across the board did all the customization itself by dynamically displaying the time and a message related to that daypart.
Think of it this way: For a fraction of your media spend, you can have multiple banners "stacked" in a single banner file, ready to react to a time and date without lifting a finger over the course of the campaign.