You can make a watermark in many programs - Illustrator, Photoshop, Lightroom, FastStone, Irfanview, GIMP, or many others.
I am not aware of any program that makes a watermark for you, which is kind of what it sounds like you're asking. You still have to make it in whatever program you choose.
You could hire someone to design one though, and then make it in some program and then send you the file. All the file is is a brush or a picture that is overlaid on top of the picture you want the watermark to appear on.
Actually, if you fill in the exif data copyright line with "something," Lightroom ail make that line of data into a simple textual watermark for you.
You're right - I wasn't thinking of it that way. In that case, FastStone and I believe Irfanview can do the same thing - you don't have to actually make a file; you just fill in a form with the text you want and the program does turn out a watermark from it.
I find that ImageMagick gives me the greatest control. You can write a short script (or, if you don't feel like programming, have someone else write the script for you) to watermark large sets of photos quickly with a single command.
This has the added advantage of allowing you to do the watermarking operation without any graphical interface. You can do it all from the command line -- very useful if you want to do the processing on a remote web server instead of on your local system.
LOL.. the best program is Photoshop and your own design. I use SmugMug to host images and Lightroom to manage and I have my watermarks loaded in both. With 1 click or 2 I have the effect I want and I can easily adjust the look or effect.
Well, really, the best program is Illustrator, but yes, the second-best is Photoshop.
If there are no plans to ever make the watermark and/or logo smaller or especially larger than the originally created size, then PS is fine. If resizing is a possibility and one wishes to do it without any loss of quality, then a vector-based program (Illustrator) is far superior to a bitmap-based program like Photoshop.
I don't know how decent is it for your taste, but this small utility is pretty convenient for watermarking -- I created a transparent image in .png format as my logo and use it all the time. I can move my logo around the frame, scale it, etc.
More, sometimes I even use this tiny utility for some minor cloning and healing, on the fly. Of course, it's just a very small and extremely fast piece of software, not a full fledged program. But sometimes less is more.