In no particular order, four ‘live’ search engines worth a look – any more that should be on my radar?

Topsy 
http://topsy.com 
In their own words: “Topsy listens to the conversations taking place all the time on the living, social web. This is the rapidly growing, exciting world of Twitter, Blogs, Flickr, Digg, Yelp, Identica and many other communities. People use these communities to share reviews, opinions, messages, comments and discussions about things. Topsy indexes those things. Topsy indexes what people are talking about.” 

Scoopler 
http://www.scoopler.com 
In their own words: “We aggregate and organize content being shared on the internet as it happens, like eye-witness reports of breaking news, photos and videos from big events, and links to the hottest memes of the day. We do this by constantly indexing live updates from services including Twitter, Flickr, Digg, Delicious and more. When you search for a topic on Scoopler, we give you the most relevant results, updated in real-time.” 

Microplaza 
http://microplaza.com 
In their own words: “We wanted a way to discover relevant and interesting items from the people we follow on Twitter. Most of the time something interesting is a link shared by a friend or colleague. So we built MicroPlaza to deliver us the filtered links from our Twitter timelines. It’s our discovery engine, our personal newswire and just so god damn addictive!” 

Tweetmeme 
http://tweetmeme.com 
In their own words: “Tweetmeme is a service which aggregates all the popular links on twitter to determine which links are popular. Tweetmeme is able to categorize these links into categories and subcategories, making it easy to filter out the noise to find what your interested in.”