Pa,
What software do you use for post processing? Most apps allow you to add text to your pictures.
I use PaintShopPro 9. What I now do for mine is to create a new vector layer which has an opacity of 30% and the put the text on that. When I merge them, I get a much more subtle watermark. e.g.
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In theory, you could even put text like that across the middle without detracting too much from the image.