If you have NewBlue Titler Pro I or II, there are a number of interesting images and textures here:
[I]C:\Program Files (x86)\NewBlue\Titler Pro for Windows\Resources\Textures[/I]
You can put the images on the timeline, change opacity, overlay, add gradient tint plus add some animation FX to make a looping animated background. I did that and it was great fun once I got the hang of it.
You can use any image or texture, but the ones that came with NB are a good start.