Reference for different looking ways of writing a character?
There are in fact a few websites out there, not to mention hundreds of book titles. You may want to try guoxuedashi.com, which has one overview page for each character (eg http://www.guoxuedashi.com/zidian/672C.html) and many sub-pages, one of them indeed with a nice overview of writing styles with pictures from historical sources, such as http://shufa.guoxuedashi.com/672C/.