I've always been curious how SEO companies manage to scale and automate?
Large SEO companies want to automate repetitive tasks, so they'll create software to scrape relevant sites along with emails, content fueled through API's to create massive websites for the sole purposes of creating own links, and automate processes such as publishing on article sites (ezine, articlezine, etc...).
I've read software like xRumer will even automate a conversation on forums, not sure to what extent though.