Community Manager: The person who manages a community on a mailing list, social network, wiki, etc. The purpose of the community manager is to help grow the community, and to keep the existing community happy and active. This work may be done solely in house on a company's own sites or may involve community management on external sites such as Twitter and Facebook.
Content Manager: The person who helps create and organize content for a company.
PPC: Pay Per Click. A type of internet advertising where the cost for an advertisement is based on how many times an advertisement is clicked on.
Reputation Manager: The person who monitors social media for a brand and then implements a strategy to deal with various types of reputation related issues.
SEO: Search Engine Optimization. There are generally three types of search engine optimization to be done: Link building, back end improvements, advertising buys. Each type is its own specialty and requires its own unique skill set.