Ah, knew someone would ask...
Quick & dirty Photoshop CS
way! I know I am up for a hardware & software upgrade soon.
Create New file, size at this time is not important
Select Background content = transparent
Select text tool and type desired content e.g. DamienMoose © 2009
Font size s not critical as long as you can see what you are doing.
If you wish copyright symbol in PS
it is ALT+0169(on Numeric keypad)
You can fade the text at this stage using opacity control on Layers control panel but I do not bother.*
At this point crop closely around your text and depending on your text size. resize the image to 200-300px wide. (if happy with result save file)
To make brush, Edit menu -> Define Brush patterns... ->name brush
That is it, now anytime you want to watermark an image just select that brush.
Size, colour and opacity are not an issue as these can all be selected to suit the image.
I tend to use a black or white watermark and use Edit-> fade brush tool (SHFT+CTRL+F) to get appropriate opacity.
* It is possible to create an Action to batch add watermarks to a number of images, if you do that it would be desirable to create the brush in the size and opacity you desire rather than adjusting later.
I hope that is all clear
If your camera sends text messages, that could explain why your photos are rubbish!