I second the nomination of decorativeiron.com
I stopped by their store in Houston last month, and they have an awesome supply of "stuff" for the ornamental builder. They had some hard to find items I had been searching for, too.
Check their books.
Also .................. what I did was to go around and photograph work. Other people's work. My work. Commercial work. Work in malls, hotels, etc. Anytime you see something nice, take a picture.
Then you can draw your "cartoon" ( a sketch of what the final ornamental iron piece will look like ) and take some from this picture and that picture. Pictures make it a lot easier to arrive at a final design, and to get it right.