Sean Moffitt has this interesting post. These traits seem so true when I look at people around me who I get influenced by.
I find people who are information hungry are the guys who spread the word the most. Also, people who adopt technology/products earlier, tend to spread the buzz faster, as it just gives them a kick to talk about things people around them have not experienced or know. Lastly, passionate people drive passionate discussions around products. They cannot be ignored. Consumers have an attraction for such people as they are honest, truthful and unbiased. Hence, they carry a far more credible WOM when they talk or refer about products.