“When you search for something on Topsy, such as “spaceX“, it finds snippets of conversations that match what you’re looking for. Topsy results are the things people link to, when they’re talking about your search terms. Topsy ranks results based on how well they match your search terms, and the influence of the people talking about them.”
So, another search engine. But this one does have quite a neat feature: check out the experts section. Now, as is often the case, it’s not easy to figure out what they class as an expert, and that’s why directories such as WeFollow can offer a better alternative (ie it’s people voted for by people). But, it’s still another quick way to identify influencers for a specific subject area.