The AnimatedGif class might be extremely useful to you, especially if you want to create customized banners in real time that catch the user's attention.
This class would be difficult to create without the great GDI+ methodology that the .NET Framework provides. Using the Bitmap.Save() method saves a lot of development time and code.
Microsoft has obtained a license from Unisys to use the GIF file format and other LZW technologies that are covered by the Unisys-owned U.S. and foreign patents in a number of Microsoft products. However, this license does not extend to third-party developers who use Microsoft development products or toolkits to develop applications. As a third-party developer, you need to determine whether you need to obtain a license from Unisys to use the GIF format or the LZW technologies.
A little knowledge of the GIF file format will provide all the code needed to put the individual images together into one big animated GIF file that, plus some knowledge of the .NET IO namespace!