In many cases, finding some information using a search engine is an iterative process: you type a query, study the results and then you adjust your keywords. Sometimes your query is too ambiguous and you need to clarify its meaning by adding or subtracting keywords.
Xippee is a plug-in that makes it easy to refine your query using words from the search results pages. Let's say that you want to find some news about the Chrome game and you search for [Chrome]. Most of the results are related to Google's recently-released browser, so you can just select "Google", click on the "-" button and you'll get the results for [Chrome -Google].
Xippee works in Internet Explorer 7, Firefox, Opera, Safari and you can use it in Google, Yahoo and Live Search.