For those who are interested in a more informative search instead of ads on the right, you may want to take a look at the Googlepedia extension.
The Googlepedia extension is activated when you google something. Instead of displaying your search results for a particular item, it actually performs a search at Wikipedia as well and displays the results in a window off to the right of the Google search.
This is especially useful for people who don't know what a certain term means. If someone was looking for "what is RSS" and what it stands for, you would type it into Google. The Googlepedia extension takes it a step further and automatically brings up the Wikipedia entry for RSS on the right of the search results.
The Googlepedia extension should take the place of the multicolumn I just reviewed on last Friday (actually Monday). This extension gets a 5/5 in my book.