Usability: This term refers to how "user friendly" a web site and its functions are. A site with good usability is a site that makes it easy for visitors to find the information they are looking for or to perform the action they desire. Bad usability is anything that causes confusion or problems for the user. For example, large Flash animations served to a visitor with a dial up connection causes poor usability. Easy, intuitive navigation and clear, informative text enhance usability.
Viral Marketing: Also called viral advertising, viral marketing refers to marketing techniques that use pre-existing social networks to produce increases in brand awareness. The awareness increases are the result of self-replicating viral processes, analogous to the spread of pathological and computer viruses. It can often be word-of-mouth delivered and enhanced online; it can also harness the network effect of the internet and can be very useful in reaching a large number of people rapidly. Source: Wikipedia
White-hat SEO: An approach to SEO which follows an ethical approach of what is generally agreed as acceptable best-practice within the industry. It is the opposite of black-hat SEO
XML Feeds: A form of paid inclusion in which a search engine is fed information about an advertiser’s web pages via XML, rather than requiring that the engine gather that information through crawling actual pages. Marketers pay to have their pages included in a spider-based search index based on an XML format document that represents each page on the advertiser site. Advertisers pay either annually per URL or on a CPC basis – and are assured of frequent crawl cycles. New media types are being introduced into paid inclusion, including graphics, video, audio, and rich media.