Not sure about making text "wave" but there are a number of resources online to create an animated GIF. A couple of them are:

Picasion - Create GIF Animations online - Create avatar from Picasa Web or Flickr
gifninja.com - create a gif from existing files

Hope this helps.

Bill

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To make an animated .gif, I design in photoshop, then make my animation in imageready, it's the best way for advanced animations.

I recommend you create the .gif in photoshop and then make your animation in imagerady as said Elaina

Thanks