Our current banner system does have an upgrade to utilize swfs, but their site is down. Tons of people are pretty furious about it, apparently it's down for good. I found another system we can use, but I need to talk to Kelli about it. For the time being, could you make an animated gif or a static image? I'll let you know what's up, just as soon as I know myself.
Well, gifs only consist of 256 colors maximum. Making complex animations wont always look the greatest. If you do simple animations, like brief fades or just frame changes, they'll work the best.