I use a program called WinWatermark Pro to add watermarking to my diagrams for added protection against image theft.
It would be nice that during the export process that I can enable this feature that was set within my preferences. The program would know which fonts were installed on the local machine and have the ability to select font size, tile, rotate, increase/decrease x,y positions, colorize, and change opacity based on my selected choices.
This is a completed diagram that was processed by WinWatermark:
Fretboard.jpg
Thanks,
ShredDead
http://www.ShredDead-Metal.com