From the MIT b l o g d e x site:
"'Weblogs' are a relatively new method of distributing personal news, essentially an individual's log of activities, news, and thoughts presented in a public manner on the web. As a publishing medium, weblogs are ultimately democratic, often as timely as traditional news sources, and have a potential distribution much greater than print media. One problem with these personal information sources is the inability to find an audience. Blogdex is a system built to harness the power of personal news, amalgamating and organizing personal news content into one navigable source, moving democratic media to the masses."
BLOG comes from the word weblog. It is a personalised selection of weblinks which can be created by anyone who codes HTML. It's the original portal concept, and there is now free software available which will help you start your own blog. This article by Rebbecca Blood provides an interesting commentary on the History and Context of Weblogs, and this blog portal contains links and resources for people who are new to blogging.
Last week's edition of KFSN mentioned a news search engine which is blog-based - daypop. Of course, there are many indymedia sites which contain commentaries and discussion points around each item that is posted. Blogs can be community based (e.g. slashdot, the ultimate indymedia blog for computer geeks). Perhaps of more interest to development and human rights workers is Alternet, which expresses independent media reviews of current events. b l o g d e x is a good place to begin.