Spacilus is a Bayesian "spam filter" for Google searches.
Everybody knows the problem: Among a typical list of search results you usually find a lot of entries that do not offer any real value towards your search request but consist of a bunch of links directing you to some shopping site or lure you to some website that might try to play all sorts of tricks (viruses, Trojans, dialers, etc.) on you.
Spacilus, helps you by using Bayesian statistics to categorize search results. Put simply, Bayesian classification looks at the joint probabilities of a search results words and phrases to belong to a certain category. For example, a search result that contains a phrase like "price comparison" will most likely belong to a category "Commercial" or "Spam" rather than to a category "Informative".
As a matter of fact, after first installation Spacilus does not know how to categorize search results at all. Instead, it will adapt to your very personal preferences. Next to each search result a set of buttons invites you to categorize it yourself and to train Spacilus at the same time. This way, click by click, Spacilus' guesses about search result categories will improve.