Whenever I start on a new custom, the first thing I do is find a few good pieces of source art online. I arrange them together on a single page and print them out in color. I keep these sheets onhand while I am working on the custom. Here are the sites I use to find source art and costume references:
This free Marvel encyclopedia is a wealth of information. As of this posting they have 44,810 images in their database. They also have extensive character bios, including origins, history, powers, trivia, and references.
This is the best site for showing all of the costumes of a particular character. The stylized images translate easily into minimate designs.
Here you can get the info straight from the horse’s mouth. They don’t have the same variety and quantity of information as the Marvel Database Project, but you can usually find different images here.
This site has miniature printable versions of major Marvel characters (as well as other licensed properties). The images are great for customs because they are mostly a classic, straight-on pose with nothing blocking any part of the character, as you sometimes find on other sites.
If all else fails, and I am unable to find the character in my own comic collection, this is my last stop. If you are searching for a Marvel character it helps to put the word Marvel as a search keyword. For example, “Marvel Cyclops” will get you much better results than just “Cyclops”.
How about you guys? Do you have any other sites that you use?