Blekko, a new search engine in the works since 2007, launched as a public beta Monday. Like Wikipedia, the site leverages the work of volunteers; in Blekko’s case, they categorize the Web in an effort to weed out malware-ridden and spam sites. Curators do this by creating slashtags for topics they like, such as “U2/music,” for example. They can collaborate as they create slashtags and can slash through heavily spammed categories so users will know to avoid them. The team behind Blekko previously founded the Open Directory Project and Topix.net.