A great technique in adding interest to a graphic is to add opacity to a background image.

If the graphic has been built-up in layers, it is then possible in Photoshop or Fireworks to change the opacity of the background image. The example give next shows an example from Fireworks:

The following gives a 50% opacity:

Next 25% opacity:

And finally 10% opacity:

In this case, possibly 25% gives the best contrast between the text, and the background image.

If you're saving images with transparency always remember to store them as PNG files, as this preserves all the layers and meta information. If possible export the file to a GIF file, as GIF files tend to give a much smaller file size, and they are supported by more browsers.