If you want to see what's most popular on Facebook at any given time, then you'll want to look at Booshaka, which follows trending topics in categories ranging from News to Gossip to Games on the world's most popular social networking site.
According to Booshaka, a trending topic means that it's getting a lot of buzz, is relatively recent, and is gaining popularity, fast. So, in News right now, trending topics are Nearly 1 in 5 Americans Think Obama is Muslim - CBS News, Last U.S. Combat Brigade Leaves Iraq, and Baby slapping aboard flight sets off debate - Yahoo! News. Each of these news items shows how many people have "liked" it on Facebook, how many discussions there are around it, as well as other pertinent statistics.
I'd use Booshaka simply because the name is very fun to say (booSHAKa! say it loud!), but it's actually quite a useful way to see what's shakin' on Facebook. Give it a try and see what you think.
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