Apps - A shortened version of a computer application or software.
Blog - A type of website (web_log) that is frequently updated. Readers have the ability to comment on articles.
Digg - A social news website that allows visitors to vote up or down on stories and the most popular stories appear on the front page.
Facebook
Feed - A data format that is used to provide readers with content that is frequently updated.
Flickr - An image and video hosting website. It is in large part used by bloggers and website owners to host the images that they use online. It is a free account for basic and a there is a paid Pro version.
Forum - Web forum or message board is an online discussion website.
Linkedin - A social networking site for business professionals
Mashable - An Internet new blog that regularly writes about social media - Facebook, Twitter, MySpace, etc.
Microblog - A blog that contain less content in entries and postings. Twitter or Plurk are perfect examples.
MySpace
Ning - A social networking website that allows you to create your own social network around your favorite cause or interest - your network within a network
OpenID
Permalink - Commonly used with blogs, permalinks is a URL that links to an article or posting. With the content of blogs constantly changing / updating, these links ensure that the article can always be located.
RSS - Really simple syndication
Social Bookmarking - The managing, organizing and sharing of bookmarks. The website, delicious.com allows you to share your bookmarks with others.
Social media optimization - The utilization of social media to draw traffic to websites and blogs
Social Media
Social networking
Social tools
Tag clouds - A visual represenation of the main words or content of website or blog. The most popular words are usually larger or in a different color. When a word is clicked, all of the articles with those words are displayed. This is helpful for search engine optimization also.
Tags - The keywords used to describe any type of online data. This has special signficance in the SEO process. Maximizing the use of the proper keywords within meta tags and to some extent, you page content can help your website to rank higher in website
Troll - Someone who posts inflammatory, extraneous, or off-topic messages in  an online community, such as an online discussion forum, chat  room, or blog,  with the primary intent of provoking other users into a desired emotional  response or of otherwise disrupting normal on-topic discussion. (Wikipedia definition.)
Tweets - the Twitter status updates
Twitter - A microblog that allows users to send messages or tweets of 140 characters or less.
Twitterverse - The Twitter universe (there's a LOT going on out there...)
Videoblog - Blogging via video (sometimes referred to as vlogging)
Web 2.0 - Commonly associated with the use of social media applications that facilitate online collaboration and sharing.
Webcasting - Broadcasting over the internet through streaming media.
Webinar - A seminar on the web
Wiki - a browser-based website that is easy to access and edit via the browser. Wikis are typically powered by wiki software and are often used to create collaborative wiki websites, to power community websites, for personal note taking, in corporate intranets, and in knowledge management systems. (Wikipedia definition)