Facebook today announced that Web pioneer and Netscape founder Marc Andreessen has joined its board of directors. Currently co-founder and chairman at Ning, Andreessen is an investor in several Internet startups. A prominent Silicon Valley veteran, Andreessen co-founded Ning as a complementary platform to Facebook that allows people to create their own social network with any design, any feature set, and in any language. He also authored early Web browser Mosaic and was co-founder of Netscape Communications. Andreessen