I can only find ABS and PLA on your site. Wood, flexible, and carbon fiber reinforced would really add to your credibility. 500g rolls are ok but I'm sure there will be people who want to find larger (1kg+) as well so you'd have to be able to supply that as well. 1.75mm and 3.00mm of course.
I like that you have some information links on the homepage, maybe add a menu tab at the top so it's more visible. I like muckychris's idea of organizing the types and sizes more. Make it easy for us to find what we are looking for!