I had been hearing about Wolfram Alpha for a while. I manually went to the web site a few times, and had mixed results. Since I use Google regularily, I figured if I could compare the results from Google and Wolfram Alpha side by side, I could see which one is better.
This Firefox add-on modifies the Google search results page to contain the results from Wolfram Alpha. I ran this for a while to compare the results between the two search engines.
For many of the search terms that I looked for, Wolfram Alpha did not return any results. Maybe , I wasn't formatting the query in a way that Wolfram Alpha wanted. I have since uninstalled that add-on, and will probably not be using Wolfram Alpha.