Below is a list of websites that I have found useful in writing this history
If you believe that I have referenced or used your site and I have not listed it here, then please contact me and I will be happy to remedy the situation if that is the case.

The Alternate History Discussion Boards A great place to discuss the What-If's of history and the site where I post most of my work.
The Warship Projects Discussion Boards These forums are also great! You can ask questions about real ships or designs that never left the drawing boards. There is also a section in which to post your own concept ideas to try them out.
Furashita's Fleet Furashita's Fleet or Grand Fleet is a concept board game as far as I can tell, but the site includes the (fictional) histories of various Never-Were Warships from numerous nations. It is useful to see where historical proposed designs may end up after modification.
German Naval History This is another useful resource site for me. It lists all constructed and many proposed German warships from the late 19th Century until the end of World War II.
Model This site contains various pictures of models of real and Never-Were ships. Nice if I want to work out what camouflage scheme a ship may carry, or where AA guns would potentially be sited.
NavWeaps NavWeaps or Navy Weapons lists all the major navies weapons and some minor navies weapons from 1880 until the modern day. An invaluable resource tool!
Wolf's Shipyard Never-Were Designs This site contains several never-were designs or concept ideas for various navies from World War I and World War II. If I am stuck for ideas, this site can help me out!