What if searching on the web worked the way it did in real life?
When your readers search for information in real life, their first step is to typically seek out a friend for the answer. If their friend doesn't have the answer they need, someone in that friend's social network may. Eventually, they get an answer they trust, because it came from a source they trust. Your readers can now have that same experience on the web and it all starts with the source they trust. That source is you, the blog publisher.
The Lijit search 'wijit' allows your visitors to search through not only your blog content, but also your extended social network. You can combine a number of your social networking accounts(delicious, mybloglog, twitter, youtube, flickr etc.). When you install the widget on your blog, all of these accounts are indexed and searchable through the widget.